I've come across these people before - Wikipedia is good here - but this quote from Black Mass, by John Gray, is pertinent:
...Whether the people they attracted were affected by war, plague or economic hardship, these movements [inspired by millenarian beliefs] thrived among groups who found themselves in a society they could no longer recognize or identify with. The most extraordinary was the Brethren of the Free Spirit, a network of adepts and disciples that extended across large areas of Europe for several centuries. The Free Spirit may not have been only a Christian heresy. The Beghards, or holy beggars, as followers of the Free Spirit were sometimes known, wore robes similar to those of Sufis, who preached similar heterodox beliefs in twelfth-century Spain and elsewhere, and the Free Spirit may also have imbibed inspiration from surviving Gnostic traditions, which were never only Christian. In any event, before they were anything else - Christian or Muslim - the Brethren of the Free Spirit were mystics who believed they had access to a type of experience beyond ordinary understanding. This illumination was not, as the Church believed, a rare episode in the life of the believer granted by God as an act of grace. Those who had known this state became incapable of sin and could no longer be distinguished - in their own eyes - from God. Released from the moral ties that restrain ordinary humanity they could do as they willed. This sense of being divinely privileged was expressed in a condemnation of all established institutions - not only the Chruch but also the family and private property - as fetters on spiritual liberty.
It might be thought that mystical beliefs of this sort could not have much practical impact. In fact, interacting with millenarian beliefs about a coming End-Time, they helped fuel peasant revolts in several parts of late medieval Europe. In the town of Munster in north-west Germany this volatile mix gave birth to an experiment in communism....
If I'm honest, I feel a lot of affinity with the Brethren, though I'd take issue with any suggestion of exclusivity (as Gray implies) in terms of the experiences that have brought me to this point. Much better in this regard is the approach of Hugh Brody, who has identified a fault line between cultures separating those oriented towards Hunter Gathering and those towards Agriculture - with farming dominant in the 'developed' world, and leading to town and city-dwelling, institutionalism and much of the drive behind politics and technological development. I would therefore situate mysticism not with Hunter Gatherering, but with the realisation that fundamentally different cultural paths are open to anyone, and that therefore, what it means to be human is revealed at a point 'before' such cultural allignments are made.
I reached this realisation after making a six-year adult commitment to Evangelical Christianity, and a subsequent eight-year deconstruction of that commitment. I see no reason why, in the process of growing up, everyone shouldn't pass through some variation of this journey. It need not include passage through an institutional religion. It is probably a natural human process. It might not be tied to a fixed age, though maturity is traditionally recognised as occurring around the thirties - the age at which grandparenting becomes possible, when one becomes less focused on parenting children, and more on parenting the parents they have become; on contributing to village debates; on achieving eldership; on shaping a community's culture, having grown up within it.
What is unusual about periods when groups like the Brethren become visible is that because of culture shifts, different cultural patterns exist in a highly visible way alongside one another. Moreover there may not be an obvious lead towards one pattern above the others. It is not, therefore, surprising to find people stripped of one culture and unalligned to the next. These people may well find themselves nomadic, naked, unaffiliated to institutions and traditional moral formations, and whilst some (but perhaps not all) utopian promises might offer temporary and appealing answers, one can also see that if premature formulations are held out against, maturity might develop, out of which these people can formulate and grow/build wholly new cultures.
We are probably in such a time - the death of old certainties, the reality of environmental degradation, multiculturalism, globalisation, the Nano-technical Information Age. Not surprising then that increasing numbers of us might look and behave like holy beggars, at least until our new cultures grow. I'm guessing this isn't the last we've heard of the Brethren of the Free Spirit.
Oh, and John Gray's from Tyneside.