Hadewijch: Mystic or theologian?

and theology – a problematic dichotomy that has recently been reflected upon. Mark McIntosh, in the preface to his book Mystical Theology , recognises that there is often an ‘unarticulated agreement that the texts and practices of spirituality are simply not suitable for involvement in the academically respectable tasks of religious studies or theology’ and have no place in ‘scholarly genres of logical argument’ (McIntosh 1998:x). He believes that one must not lose touch ‘with that mysterious language by which humanity and the ultimately meaningful have access to each other and are able to enter into dialogue’ (McIntosh 1998:x). This implies an appreciation of the not-so-common genres of theological discourse. This article will start with a reappraisal of some definitions of being a theologian. This will be followed by a broad introduction to the life, context, work and reception of the 13th-century Hadewijch. Examples of recent appreciation of her theological depth, as well as the possibilities for further research, will be provided. This article engages with the reception and naming of women by contemporary historians and theologians. The core question is as follows: when is a woman received as a theologian? This question is looked at via the works of Hadewijch, a 13th-century Flemish writer. Scholars easily group together women from the High Middle Ages as mystics, referring to the experiential character of their theology and their writing in the vernacular. These criteria of gender, language and experience then disqualify them as theologians and qualify them as mystics. In this article, the dichotomy between spirituality and theology is revisited and examples of a growing discourse where Hadewijch and some of her contemporaries are called theologians are given. The genre of theology is then widened to recognise the worth not only of scholastic discourse but also of vision, poetry and bodily experience. Contribution: The renaming of historical woman figures is of utmost importance in the understanding of what constitutes women theologians in the present day as well as for the healing of the divide between ‘spirituality’ and ‘theology’.


Introduction
When is a woman deemed a theologian? The theme of this topical collection assumes that women are recognised as theologians. In most parts of the world, theological education only became accessible to women in recent decades. Unlike in the past, women can present their academic credentials and embrace the title of theologian. But what of women in previous centuries? How do we retrieve them and name them? What is the implication of how they are named for how we judge the content of their work?
The retrieving of women theologians is a critical task, a task that recognises the gendered reception of voices through the ages. One such 'group' that is worthwhile revisiting is the so-called women mystics of the High Middle Ages. But already in grouping them together in popular and academic language, the individual woman and her theology is shadowed by the similarities with others; her particularity is not recognised. And in calling them or her mystics, they are not necessarily received as theologians.
In this article, the concept 'theologian' will be considered, especially with regard to the inherited dichotomy between spirituality and theology -a problematic dichotomy that has recently been reflected upon. Mark McIntosh, in the preface to his book Mystical Theology, recognises that there is often an 'unarticulated agreement that the texts and practices of spirituality are simply not suitable for involvement in the academically respectable tasks of religious studies or theology' and have no place in 'scholarly genres of logical argument' (McIntosh 1998:x). He believes that one must not lose touch 'with that mysterious language by which humanity and the ultimately meaningful have access to each other and are able to enter into dialogue' (McIntosh 1998:x). This implies an appreciation of the not-so-common genres of theological discourse. This article will start with a reappraisal of some definitions of being a theologian. This will be followed by a broad introduction to the life, context, work and reception of the 13th-century Hadewijch. Examples of recent appreciation of her theological depth, as well as the possibilities for further research, will be provided. This article engages with the reception and naming of women by contemporary historians and theologians. The core question is as follows: when is a woman received as a theologian? This question is looked at via the works of Hadewijch, a 13th-century Flemish writer. Scholars easily group together women from the High Middle Ages as mystics, referring to the experiential character of their theology and their writing in the vernacular. These criteria of gender, language and experience then disqualify them as theologians and qualify them as mystics. In this article, the dichotomy between spirituality and theology is revisited and examples of a growing discourse where Hadewijch and some of her contemporaries are called theologians are given. The genre of theology is then widened to recognise the worth not only of scholastic discourse but also of vision, poetry and bodily experience.

Who (what) is a theologian?
This question has two foci. The first is how being a theologian is understood in present discourse . The second addresses  how figures from the past are received and named and what  the implications are for a present understanding of what a  theologian is. Hadewijch (fl. 1240) was a contemporary of Albertus Magnus (1200-1280), Bonaventure (1221-1274), Duns Scotus (1265-1308) and Thomas Aquinas (1224-1274) -all well-known thinkers and scholars of the 13th century. These scholars, Dominican and Franciscan, are remembered as theologians.
Prevot (2017) recognises a discrepancy that will be elaborated in this article. Prevot (2017:107) calls for 'recovering a tradition of women theologians' and argues that the experiences, thoughts and actions of centuries of Christian women have 'often been gathered together under the somewhat dubious category of "spirituality"'. Prevot (2017) evaluates the use of this category as: [D]ubious insofar as it invites a contrast with theology and insofar as it contrast manifests and reinforces a problematic construction of the 'feminine' as a spiritual figure and the 'masculine' as theologian. (p. 107) He addresses this distinction because it perpetuates the dichotomy between theology and spirituality, a dichotomy that impoverishes both.
In Prevot's (2017) argument, two issues are raised. The first is the dichotomy between spirituality and theology amidst a growing recognition of spirituality as an academic discipline, and the second is the stereotypical placing of women within this dichotomy on the 'side of' spirituality. The focus of this article is a reformulation of what is deemed theology that does not perpetuate these divisions but gives criteria for 'naming' women from the past as theologians. This includes a reappraisal of the worth of mystical experience as a source of theological knowledge.
As Prevot (2017) writes: [B]y locating women's work in a category of spirituality set apart from theology, we risk perpetuating a centuries-old sexist assumption that women are not likely to contribute very much (if anything) to conceptually rigorous and communally normative thought about God. (p. 109) If the word 'spirituality' is used to categorise women of the past, it can imply a distinction as 'other than theology', with a belittling connotation. Even if spirituality becomes a fullfledged academic discipline, it still has associations of being less theological. If women of the past are to be called theologians in earnest, we need to reassess what we mean by the word 'theologian'.
The importance of this naming is formulated by Prevot (2017:110): 'how we think about past generations of women continues to affect current perceptions and realities for women and men in the present'.
This leads to another important question: whether a very broad and inclusive understanding of what constitutes a theologian will be helpful in this specific discussion? Martin Luther wrote: '[b]y living -no, much more still by dying and by being damned to hell -doth a man become a theologian, not by knowing, reading or speculation' (WA 5, 163 quoted by Moltmann 1999:193). This definition recognises the experience, struggle and formulations of any believer. Jürgen Moltmann (1999:189) also opens the floor for more than academics and university scholars. Reflecting on his first congregation -a farming community -he writes: [E]very Christian, man, and woman, young or old, who believes and thinks at all about belief, is a theologian. In those farming families I learnt to value 'the general theology of all believers'. (p. 93) He goes on to also say that theology is not only for believers, because God is not just a God for believers (Moltmann 1999:191). For Moltmann, the old theological saying is true that 'to know God is to suffer God'.
In this argument, Moltmann brings all contextual reading into the frame of theology. This is a liberating insight for believers whose own struggles with God are then taken seriously and acknowledged. In 20th-century theology, especially different strands of liberation theology, contextual reading became a space of social justice and bringing voices in from the margins.
However, does this broad definition help us with a more historical exercise of retrieving women mystics as theologians? This 'general theology of all believers' as a historical lens is not necessarily helpful in a process of retrieving the broader influence of the writing of someone who is already stereotyped and named. The moment everyone becomes theologians, the concept collapses into itself and further recognition of bodies of transforming material is not always accepted.
With the above in mind, more specific questions can be posed, which can be used in dialogue with 13th-century Hadewijch. Is a theologian someone who writes about God and their relationship with God in the vernacular? Referring to a woman in medieval times, this could be called 'audaciously novel', as formulated by Alois Maria Haas to describe the use of vernacular to record a relationship with God (Haas 1998:141). Mir (2018:181) refers to Bernard McGinn's naming of lay religious women as 'medieval women vernacular theologians'.
Bearing in mind the possibility of a vernacular theology in the Middle Ages, one can also ask, 'what genre is "fitting" for theology?' Is a theologian someone who reflects on specific experiences of God, who finds language not in scholastic discourse but in rhyme, allegory and letters, or is it restricted to scholastic discourse and rational methods of argumentation and disputation? The phenomenon that is called 'mystical writings' in these centuries also asks for a reconsideration of defining mysticism. Bynum (1998) remarks that, because most of our information about women in medieval times comes from male authors of biographies, it is especially important: [F]or future historians to turn to detailed study of those works in which women wrote about their own visions and mystical experiences and about life among the sisters in their households, beguinages, and convents. Such works -letters, vision collections, nuns' books or collective biographies, hagiography, rules, religious poetry, treatises of spiritual advice, and even autobiography -proliferated, especially in the thirteenth century, as the growth of written vernacular languages gave women new access to literary expression despite their exclusion from the theological training offered in universities. (p. 136) These literary outputs of women can form the lens through which their life and work can be recognised as that of an individual. These disparate women over geographical barriers are often grouped together as if the common denominator, namely their gender, dissolves all other differences and authenticity. Bynum (1998:137) identifies work done from feminist or traditional medievalist perspectives where feminist critical readings focus on renunciation and negative stereotyping of sexuality and the lack of worldly power and sacerdotal authority of these women. For her (Bynum 1998): [T]he task for future historians of women's piety is not only to devote more detailed study to texts by women but also to pay attention to the full range of phenomena in those texts, no matter how masochistic or altruistic, unattractive or heroic, peculiar, amusing, or charming such phenomena may seem, either by modern standards or by those of medieval men. (p. 137) These women's texts are usually grouped together by common denominator (being women) and rubrics 'related to gender or to themes implicitly or explicitly linked to women' (Dailey 2011:317). This categorisation, according to Dailey (2011:317), creates a host of long-term problems: Categories such as 'women's mysticism' or 'medieval women writers' tend to foster essentialist generalisations (for example, 'all women writers/mystics, regardless of their historical situations, write/act in such-and-such a manner') as well as particularisation and devaluing (for example, 'this is merely a group of women and therefore offers no insights into humanity, it is not central or crucial or weighty -it is not authoritative'). (Dailey 2011:xiii) As McIntosh (1998) wisely comments: What an irony it would be if the academicians finally allowed the return of spirituality as a conversation partner in the university, only to consign it -as did many late medieval ecclesiastical and university authorities -to a non-theological realm labelled, appropriately, private devotion. (p. 23) Retrieval and renaming some of these women writers has been undertaken. Denys Turner in Julian of Norwich: Theologian describes Julian's Long Text of Revelations of Divine Love as 'one of the great works of Medieval theology in any language by an author of either gender' (Turner 2011:x). He recognises that this text does not fit comfortably 'within standard taxonomies of theological genre in her own times' (Turner 2011:x). Julian does not write from a biblical passage, like the monastic tradition of her time, or from a statement, like the scholastic tradition of her time, but from her own intensive experience. She reflects 'through a process of progressive intensification and complex elaboration of particular and personal experience' (Turner 2011:xi) that leads to her struggle with the cross and the existence of sin but always in dialogue with God.
In describing what her theology is not, Turner gives clues to what a theologian can be. According to Turner (2011:x), Julian's theological reflections 'are elicited through a process of progressive intensification and complex elaboration of particular and personal experience'. It is therefore not theology derived deductively or inferentially extruded from some set of general theological principles or derived directly from the exploring of cited scriptural sources (Turner 2011:x). Turner (2011:xi) considers her style much like that of the 'variations movements of classical sonata form'. She explores, tests and expands.
Turner (2011:217) finds Julian's way of doing theology helpful in these days in which theological fragmentation is experienced. One can possibly see the spirituality versus theology dichotomy as a type of fragmentation. Important for this article is Turner's insight into the possibility that theology can be presented in a different format and still qualify.
As Prevot (2017:116) discusses, women did 'theology that [was] explicitly shaped by bodies, relationships, experiences, prayers, actions, and so on'. What is the aim of such theology? To inform or to transform? 'Mystical texts are intended to bring about transformation, but they also contain a wealth of theological content' (Dreyer 2005:xi).
A last comment before Hadewijch is introduced is the historical phenomenon that what is seen as 'normal' today, namely the possibility of a woman working and presenting herself as a theologian, could have had you killed centuries ago. Women writing outside the safe space and recognition of ecclesiastical male authority lived under threat of being condemned as heretics -as was the case for Marguerite Porete. In medieval times it was safer not to be a woman theologian. Does that mean that medieval ecclesiastical criteria can still be used to name women from that era?

Hadewijch
Why Hadewijch, or Hadewigis de Anverpia as she is named in the Rooklooster compilation (ca. 1530) (Boeren 1962 More research has probably been conducted on her genres in the vernacular than her theological contribution (at my own university, there is a shelf of books about her under literature and none in the Theological Library). Her poetry is described as sublime (Mir 2018:179) and she herself as 'een groot kunstenares' [a great artist] (Reynaert 1981:9); 'she may rightly be called the greatest poetic genius in the Dutch language' (Arblaster & Verdeyen 2017:46). Commentators do, however, recognise that her work is not always easily understandable, especially because of the religious context. Much more work on her texts has been conducted in the Flemish and Dutch context than in English contexts.
This article does not aim to significantly broaden research conducted on the specific content of her work but rather reflect on the implications of retrieving her and her genre for constructive dialogue on mysticism and theology. Beguines as a social group were prolific and prominent in these geographical areas and times, and the possibility has been raised that she formed part of such a group. Although it is never clearly stated, most scholars agree on this as a plausible context.

Life and times
The beguines were women 'who answered the call to live in poverty among urban populations in the Low Countries, Germany, and Northern France, after the example of the apostolic church (vita apostolica)' (Sasongko 2018:196). The etymology of the word is unclear and can even be traced back to a slur derived from Albigensian, meaning 'heretic' (Bynum 1988:124). These groups operated outside official sanction and were not always accepted by the institutional church, especially where it placed women in positions of preaching and teaching. They set themselves apart from the world and chose manual labour and charitable service (Bynum 1988:124). This movement flourished from about 1220 to 1318 (Dreyer 2005:106), but during the Council of Vienne an investigation was launched, and the dismantling of these communities was ordered. A popular explanation for this growing phenomenon is demographic -women were in surplus and not all had the financial means to enter a covenant. However, Bynum (1988:124) argues that one cannot claim only demographic reasons, giving examples of women of means who actively chose this kind of life as an alternative to cloistered life.
It is therefore not unlikely that Hadewijch formed part of such a group, as one recognises her work as that of a teacher. Scholars infer that she often changed her home. It seems she lived with younger women whom she taught with some authority. De Paepe guesses that she moved to another community because she was strict with herself and others: 'dat haar tot een ijzeren gestrengheid jegens zichself maar ook jegens anderen moet hebben geleid' (ed. De Paepe 1979:x). Bynum (1988:135) and Dreyer (2005) pick up on the tradition that she was 'persecuted' and neglected by the end of her life: '[l]ike the Flemish beguine Hadewijch, who was evicted from her beguinage, the grieving for lost companions was intense and never healed' (Bynum 1988:135); Dreyer (2005) states: [A] number of factors -her high standards, opposition from within and outside of the community, jealousy and an accusation that she was teaching quietism (a form of prayer that emphasized internal, personal, silent prayer over external observances)may have led to her being exiled from her community. (p. 108) Hadewijch was well educated. She was comfortable in her own language, Diets, and had a good knowledge of Latin and French (ed. De Paepe 1979:x). Her knowledge of scripture and the fathers of the church, as well as her knowledge of 'rhetoric, numerology, astronomy, music, and verse show that she was probably an educated member of the upper class', (Dreyer 2005:105). Although she wrote in the vernacular, she would have been called litteratus, which until 12th century meant to be literate in Latin (Newman 2012:226). It seems that in her lifetime, 'vernacular mother tongues privileged speech, not writing, and the earliest secular literature was meant for performance, love songs, epics, bawdy tales, and romances' (Newman 2012:226 Her poems in stanzas Are a reflection of her time, when love poetry about Minne flourished and was seen as a type of 'gehumaniseerde religiositeit' [humanised religiosity]. The theme of Minne as theological motive will be addressed in the next section. An example of her poems in couplets will be referred to later in this article.

Reception of her work
Hadewijch was a prolific writer, and it seems that a compilation of her work was available not long after her death (ed. De Paepe 1979:xi). The earliest trace of the influence of her mystical teaching is in a compilation of sermons from the 14th century, namely Limboergse Sermoenen. Some of her letters were translated into German in the 14th century, and she was named Sint-Adelwip, which gave her the title of a saint, as she was also well known in the Netherlands by then (ed. De Paepe 1979:xi). Although her work was never widely circulated, 'many of her ideas were transmitted incognito through the works of John of Ruusbroek' (Arblaster & Verdeyen 2017:46). This is a telling example of her influence on Ruusbroec ('Ruusbroec, het is bekend, eft zijn fundamenteelste stellingen in Hadewijchs geschriften kunnen vinden' -It is known that Ruusbroec could have found his most fundamental statements in Hadewijch's writings). His work includes many intertextual references and direct quotations (Arblaster & Verdeyen 2017:46

Hadewijch as theologian?
In recent times, the writings of Hadewijch have been increasingly appreciated for the theological nuance and depth. Examples of such scholarly recognition of Hadewijch in the following paragraphs engage with theological themes in her work. Her Trinitarian thought grounded in her understanding of Minne forms is a significant focus of this research (Mir 2018): [M]inne is a core concept in her work and the work of some of her contemporaries (e.g. Mechthild of Magdeburg). The concept of minne is derived from the courtly love songs (chanson) of her context and can be seen as replacing the Dame Amour of courtly love lyrics. (p. 184) Minne has a wealth of meaning. It refers to the one who loves, the beloved and love itself. Minne is multifaceted. As these strophes of Hadewijch clearly show: Minne has creative possibilities for writing in genres of hymns, visions, and poetry. As a 'female gendered noun in both the German and Dutch of that period' (Mir 2018:184), minne lends itself to a playful mixing of object and subject and portrays a gender fluency and reversal.
De Paepe (ed. 1979) sees Hadewijch's understanding of the meeting of Minne as an existential experience and compares it with the content of more secular courtly love songs: Anders dan bij de profane dichters is minne dus niet een verlangen dat zijn eigen volkomenheid in zich draagt, maar een existensiële beleving die in zichself goed is omdat ze, zij het niet on-middelijk, dan toch middelijk, ontmoeting betekent. (p. xxxvii) What De Paepe imparts is that the courtly love song is the not-experiencing of the woman, but Hadewijch's minne is the experience of God. This minne is more than the experience of love and cannot be separated from the one that awakens the love.
McIntosch, in engaging Hadewijch, writes that for her to experience love is to meet the Beloved (McIntosh 1998:23).
Hadewijch is deeply aware of these 'meetings', but she is not so much interested in her feelings but rather in what they communicate about the one who awakens these feelings (McIntosh 1998): The spiritual experience -in our usual sense of some sensation of inner feelings -is for her only a by-product of her participation in God, a manifestation in terms of her humanity of God's secret presence and activity. (p. 23) The default critique, especially in the Reformed tradition, focuses on the so-called subjective experience within mysticism. Both Denys Turner and Mark McIntosh critically confront this assumption: '[w]hy is it that language about God or the cosmos so often comes to be interpreted as language about self and its "experience"?' (McIntosh 1998:205). Ironically, it is mysticism that warns against the danger of paying too much attention to experience and which opts for metaphors that 'speak away' in an apophatic manner.
Sasongko (2018) focuses on Hadewijch's Trinitarian thought: 'Hadewijch believed that the Incarnate One and the Spirit of Life proceeds from the Creator God, echoing the Trinitarian thought of the Capadocian Fathers' (Sasongko 2018:200). Because Hadewijch wrote in the vernacular, her choice of words and phrases was not derived from the authority of the church 'but from the language of laypeople' (Sasongko 2018:200); from the margins of power, her vernacular was the experience of a devout woman of her society (Sasongko 2018:203). This 'lay language' does not, however, make it less theological, as we know that the vernacular became the vehicle of theological communication of the later Reformers.
Again, as Sasongko (2018:200) shows, for Hadewijch minne was the mystical bond of intimacy 'between the human lover and the Trinity through which the soul experiences its relation to God'. Hadewijch describes the struggle for spiritual maturity 'as "growing to be God with God" or as becoming Minne as God is Minne' (Arblaster & Verdeyen 2017:47, referring to Visions 7 and 3).
Hadewijch, however, never negates the role of reason. Dreyer (2005:50) reminds of the medieval phrase amor ipse intellectus est [love is a kind of knowing]. The distinction between reason (ratio) and knowing (intellectus) refers to intuitive awareness beyond conceptual knowing (Dreyer 2005:50). Hadewijch did not disdain reason; it is the 'part of a person that is renewed and enlightened as a result of ecstatic, affective, mystical experience' (Dreyer 2005:113). Love without reason is incomplete, and reason 'has a key role in the process of discernment' (Dreyer 2005:113); 'reason safeguards Hadewijch's love affair with God from being closed in on itself' (Dreyer 2005:113). In Letter 18, Hadewijch writes: Reason cannot see God except in what he is not, love rests not except in what he is. Reason has its secure paths, by which it proceeds. Love experiences failure, but failure advances it more than reason … These two, however, are of great mutual help one to the other; for reason instructs love, and love enlightens reason. (Dreyer 2005:115) Much potential research is hidden in the deconstruction of the modernist assumption of mysticism being nonrational. It is quite possible that the reception or nonreception of Hadewijch outside her time was determined by a modern suspicion of experience as the antithesis of reason.
Johann Beukes also wrote on figures like Mechthild of Magdeburg (2019), Hildegard of Bingen (2019) and Hadewijch (2020), to name but a few, playing with titles of theologian and philosopher to reappraise their contribution to medieval thought. His reappraisal of these medieval women opens up possibilities for further research, also in a South African context. Beukes (2020:1) distinguishes Wesensmystik from Minnemystik and recognises Hadewijch as an example of the second and therefore her work can be described as deeply theological in content. Beukes (2020:9) concludes that '[t]he profound experience-driven and theological contents of her Minnemystik position Hadewijch in the midst of us as one of the most essential female thinkers from the High Middle Ages'. Mir (2018) refers also to her use of minne in her Trinitarian work and concludes with a rhetorical question: [A]nd is the dynamic structure of her work, with its constant shifts of grammatical perspective, gender perspectives and use of dynamic opposites, not merely a set of literary devices but a signifier too of the core of her theology? (p. 210) The focus of Tautz's (2019) (Haas 1998:142), and her most important tool to express the paradox of experience and nonexperience is the vision, where she combines theology with intense imagery (Haas 1998:142). Sasongko (2018:203) reflects that in her visions 'her understanding of God and the humanity of Jesus was not based on the accepted interpretation of the Holy Scripture by the ecclesiastical hierarchy, but on her vision'. It was also vision that was open to the charge of heresy in her context.
The above are just a few examples of the wealth of possibilities for theological reflection that can still be tapped into in the work of Hadewijch.

Renaming Hadewijch
Hadewijch: mystic or theologian? Why does it matter? It matters because in naming and retrieving, it is possible to give recognition to women in the past as individuals with their own legacy and not just as one of a group of 'women mystics'. It matters because for too long theology (especially after the Aufklärung) has not recognised the inherent experiential aspect of God-talk that does not necessarily negate reason but chooses other genres and styles to make sense of God, experience and self -not only argument and logical discourse but also poetry and vision.
It matters because we do not have to follow the ecclesiastical rules of medieval society. For Hadewijch and some of her contemporaries, reception was dangerous. A woman placing herself in the position of a teacher and theologian could be burned as a heretic, as the example of Marguerite Porete reminds the reader. In retrieving, one can name them, as these words from the Council of Vienne (1312) remind (cited in Jantzen 1995): We have been told that certain women commonly called beguines afflicted by a kind of madness, discuss the Holy Trinity and the divine essence, and express opinions on matters of faith and doctrine contrary to the catholic faith, deceiving many simple people. Since these women promise no obedience to anyone and do not renounce their property of profess and approved Rule, they are certainly not 'religious' … We have therefore decided and decreed with the approval of the Council that their way of life is to be permanently forbidden and altogether excluded from the Church of God. (p. 206) Arblaster and Verdeyen (2017) rightly comment: In the eyes of the mystical authors, the human being is by no means an autonomous and isolated individual. We find in their writings something quite different to the rationalistic systems that developed in the wake of late Scholasticism, nominalism, and Modern philosophies. We do not exist by virtue of our rational faculties, however important they may be. We are more so relational beings, and it is precisely in and through these relations that we become increasingly human and divine. (p. 47)

Conclusion
Hadewijch was audacious in her writing and being. She 'stands proudly demanding Love as a lover' (Tautz 2019:91). Maybe a woman writing in the vernacular because of her bodily and visionary experiences of God was safer tucked away within the name 'mystic'. If we call her a theologian, what does this say about her? And more importantly, what does this say about the God about whom she writes in such an intimate way?

Funding information
This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.

Data availability
Data sharing is not applicable to this article as no new data were created or analysed in this study.

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The views and opinions expressed in this article are those of the author and do not necessarily reflect the official policy or position of any affiliated agency of the author.