In the Buile Suibhne, the eponymous Suibhne goes mad in battle as the result of a saint's curse. The symptoms he displays are very akin to what we could today interpret as post-traumatic stress disorder. He flees from the place of battle and ends up hiding out in the forest, running from phantoms and spirits, unable to tolerate the company of others, eating only plants. Eventually he was said to have grown feathers and flown from treetop to treetop like a bird. He is not the only geilt described in the literary tradition, and there is even a valley where the geilta, the madmen, were believed to gather until their sanity was restored.
But along with this madness came poetry. The body of nature poems attributed to Suibhne Geilt is impressive and the images are striking and powerful. His visions and terrors evolved into poignant laments and strange dialogues with trees and beasts. Whether the Irish writers believed that Suibhne was actually in communication with such spirits is an open question, but the story can certainly be read in Pagan and animist ways. Suibhne himself was described as a Pagan who attempted to kill the "saint" who cursed him, presumably attempting to preserve the old order in his kingdom rather than give his power over to the church.
Other "madmen" in the Celtic literary tradition, including Myrddin and Lailoken, were regarded as prophets -- seers and possessors of a certain "crazy wisdom." Sacred madness is a current in many spiritual traditions around the world. It's found in many Native American tribes, within Hindu and Buddhist practice, as well as in Islam and Christianity. Such traditions have their gifts and their difficulties. As someone who lives on disability with a diagnosis (one among many) of post-traumatic stress, I've looked at these roles and potentials and seen them as models for my own life in much the same way that many individuals in Siberian cultures deal with healing spirit-sicknesses by falling into the spiritual world and coming out again transformed.
By pursuing poetry as a spiritual practice I've managed to find my way to a certain amount of healing and sanity. It has exorcised many of the figurative demons that made my life a misery. In seeing Suibhne's madness as a metaphor for my own experience, I've embraced the idea of the professional madwoman and claimed the title of geilt as a badge of honor for what I've gone through. I think that poetry can take suffering and illness and turn them into art and a potential for healing and growth. It's not that poetry by itself will do this -- I've done a lot of years of therapy and medication as well -- but the work of poetry can give a spiritual focus and purpose to what feels like continual chaos and destruction. In this sense, the task of the geilt is to refuse to succumb to the pain and to work through the mists to transcend that condition and bring something useful out of the fear and the misery.
Working with the arts of the fili or sacred poet, the experiences of the geilt can be mediated and expressed. Expression often helps to clarify and understand what is happening, aiding the person to get to the root of the problems and issues, whether they are physical, spiritual, emotional, or socio-political. Techniques that help to communicate with spirits and deities as well as journeying work can help with clarity and understanding as well, as can acts of divination through seeking oracles or finding omens. Rituals to embrace the madness as a part of working through it can be effective as well, reinforcing positive patterns and activities and drawing the mind out of the obsessive circles it may fall prey to without such focus.
That said, the nature of the geilt means that control is often an illusion. Interpretation and acceptance is a more fruitful path for one with these proclivities. This is not in any way suggesting "giving up" but merely a statement that the world and the Otherworlds are vaster than we can understand and we, mere humans, have very little power over some things that happen. That isn't necessarily a bad thing, though our culture values control (or the illusion of it) very highly. It can be a relief for guilt and anxiety to let go of inappropriate responsibility.
Sometimes I joke with friends that I'm only responsible for the decay rate of the hydrogen atom, hence I don't have to deal with anything else in the universe. Obviously, that's not the case, but it does serve as a reminder to me to only claim what I'm genuinely responsible for -- and as a geilt, my own sanity and spiritual work is high up on that list. There are other priorities as well, but a geilt is an outsider, someone who lurks on the boundaries of groups and societies. That inclination to solitude is part of what marks someone as geilt but can also be a part of what helps to heal the terror and the insanity of those who have been through violent experiences, through abuse, through battle or rape or overwhelming environmental events that have destroyed their ordinary daily lives.
Within the experience of geiltadecht, madness and destruction is the foundation for transformation.