Towards the end of her life, probably near the end of the year 1579, St. Teresa was travelling with three of her nuns from Medina del Campo, across the bleak Castilian plateau, on her way to St. Joséph's, Avila. Accidentally (or, as it would be more accurate to say, providentially) she fell in with an old friend, a Hieronymite, Fray Diego de Yepes. Their meeting took place at an inn in the town of Arévalo, where he had arrived some time previously, and, as was fitting, he had been given the most comfortable room. When the little party of nuns, half frozen but still cheerful, reached the inn, there was mutual delight at the encounter; and Fray Diego not only gave up his room to them but appointed himself their personal servant for the period of their stay. They spent, so he tells us, "a very great part of the night" in conversation about their Divine Master. On the next day it was snowing so hard that no one could leave. So Fray Diego said Mass for the four nuns and gave them Communion, after which they spent the day "as recollectedly as if they had been in their own convent". In the evening, however, St. Teresa had a long conversation with her former confessor, who later was to become her biographer, and in the course of this she recounted to him the story of how she came to write the Interior Castle. The report of this narrative may suitably be given in the words of Fray Diego himself, taken from a letter which he wrote to Fray Luis de León about nine years later.3
3 The letter [printed, in Spanish, by P. Silverio, II, 490-505] is dated September 4, 1588. The anecdote is told more briefly in Yepes' biography of St. Teresa, Bk. II, Chap. XX.