The well's Irish name, Tobar na nGealt, translates variously as the Well of the Lunatics or the Well of the Naked, and both names point to the same phenomenon: for centuries, people experiencing madness were drawn to this valley, and to a companion well nearby, to drink the water and eat the watercress growing at the margins. The well is not venerated as a holy well in the religious sense, which makes its reputation all the more unusual. Its reputed power was never framed in terms of sainthood or pilgrimage in the Christian tradition, but rather in terms of something older and harder to name, some quality attributed simply to the valley itself.

The tradition of Gleann na nGealt as a refuge for those losing their minds stretches back at least to the seventeenth century, according to the scholar De Brún, writing in 1973. By the time P.W. Joyce described the glen in 1869, an entire local geography of affliction had accumulated around it. Those who came to seek a cure would cross the valley stream at a point known as Ahagaltaun, the madman's ford, and pass by Cloghnagalt, a standing stone that carries the same root word for lunacy in its name. Joyce recorded the belief in plain terms: the water, the cress, and what he called the secret virtue of the valley, taken together, would restore the wanderers to sanity. Ó Danachair, writing in 1960, confirmed that the twin wells were still locally known as the Madman's Well, and noted that many tales of cures had attached themselves to the place over the years.

The well sits within an area of dense woodland and its exact location proved difficult to pin down even for those who went looking. It is a natural spring rather than a built or dressed structure, which goes some way to explaining why it can be elusive. The watercress that reportedly formed part of the cure still grows in such places, rooted in the slow cold water at a spring's edge, and the valley retains the layered place-names, the ford, the standing stone, the wells, that map out a landscape once understood entirely through the lens of mental affliction and its possible remedies.