This week Lent begins, and throughout the world tens of thousands of people will be fasting - disciplining their bodies in relation to food and liquid intakes, or other 'consumer activities' - as part of a process of reflection, reconsideration and re-orientation of life (what the gospels call 'repentance').
Nor will this be an individual spiritual commitment only. In many cases it will have an outward looking and even political dimension. The Methodist churches in Britain and Ireland, for example, have declared 25 February 2010 a day of fasting and remembrance in solidarity with those suffering human rights abuses and persecution at the hands of an authoritarian government in Fiji.
Development and environment campaigners are also fasting. The Ecumenical Advocacy Alliance (EAA) is promoting a 'Fast for Life' on Ash Wednesday. In early to mid March I am due to meet a church communications worker up in Scotland. But he told me in an e-mail conversation that it might be water rather than coffee that we are sharing!
So what is all this about? What difference does fasting make, to whom and why?
In western societies it is often activists as much as religious communities who have been at the forefront of recovering fasting as a way of reconnecting the personal, the spiritual and the political. At its best it is, very directly, hungering and thirsting for right in the world; putting your body on the line.
As such, personal and group abstention has been part of the campaign for remission of the global debt burden on the poor. It strengthened the pro-democracy monks in Burma back in 2007. It has featured on protests outside asylum detention centres. It has also been used as a way of galvanising action over Darfur and Tibet.
Other recent ideas include a 'carbon fast' over Lent (2009) and an initiative that encouraged professional people to seek to live at the same level as asylum seekers, thus reducing their intake considerably. Church Action on Poverty has also enabled people to see what it is like to live on or below the minimum wage over the years.
The value of fasting is little comprehended these days. No doubt those who hold an incorrigibly negative view of 'things spiritual' will be tempted to dismiss it as mere punitive self-abuse for the gullible. Needless to say, its history, practice and impact is a bit more complex than that.
Self-denial can be pointless or pitiless, of course. In the gospels, Jesus warns against its manipulation by religious interests that put power before the human good. Rightly understood, however, fasting is a life-changing practice of self-examination and social re-orientation. It embodies (quite literally) the liberating discovery that we human beings are not simply the sum total of our appetites, but have been given the capacity to transcend self in solidarity with those who are denied food and justice. It reaches beyond material satisfaction towards the kind of transformative love that is beyond limited or tribal affections.
Fasting is therefore an integrative discipline, focused on how we think with our bodies, not with disembodied and unaffected minds (the conceit of a certain naive conception of autonomous reason). Human consciousness and decision-making is inextricably bound up with our being relational creatures - "dependent, rational animals", as the moral philosopher Alasdair Macintyre has put it. There is genuine freedom in this. And we learn it by exploring and directing our yearnings and actions, personally and corporately, not by theory alone.
In a voraciously consumerist society, where luxuries rather than necessities are the preoccupation of a majority, fasting also has a certain political poignancy. When the quest to possess and devour more and more takes over, our personal and social priorities are fundamentally altered. Instead, fasting points us in the direction of sharing and the otherwise unimaginable politics of "enough".
As a distinctly "spiritual" practice with broad roots, fasting also readily connects with "secular" initiatives like Buy Nothing Day and other grassroots attempts to resist the "thou shalt have no other jeans but mine" culture. That, by the way, is the wonderful title of an article by the late German theologian Dorothee Soelle. It appears in a collection of essays edited by humanist social theorist Jurgen Habermas, called The Spiritual Situation of the Age.
What people are learning through hungering for justice is that trying to come up with policies for a better world is not enough. We need changed people to want them and to make them work. That involves re-shaping our desires, not just our political hopes. At its best, that is what fasting is all about: learning to thirst for right to prevail, as Jesus puts it in the Beatitudes.
(c) Simon Barrow is co-director of Ekklesia. www.simonbarrow.net