Heaney, the Nobel laureate poet from Northern Ireland, told the Class of 2000 an ancient story from the medieval annals of the monastery of Clonmacnois in Ireland. One day, while monks held a meeting in their church, a ship appeared sailing through the air above them. When the crew dropped anchor, it caught on the church floor. A man climbed down after it, 'swimming as if he were in water,' and begged: 'For God's sake, let me go, for you are drowning me.' The monks released him, and he swam back up into the air. Heaney called this 'a kind of dream instruction, a parable about the necessity of keeping the lines open between the two levels of our being' — the level of routine meetings and practical decisions, and the level 'where the visionary and the marvelous present themselves suddenly and bewilderingly.' The line itself became one of the most quoted from any commencement speech: a poet's warning against the tyranny of pure rationality.