Erasmus of Rotterdam viewed sleep as playing a fundamental role in the functioning of the intellect and in the preservation of health. As a young man, Erasmus found the vigils imposed in the middle of the night in the monastery of the Austin Canons in Steyn too heavy a burden for him, and he mentioned them regularly among the reasons why he was not made for the monastic life. With his famous colloquy Diluculum, however, Erasmus played a part in imposing on the modern West the idea that one needs to rise early to accomplish complex intellectual work. As a corollary, but one that is much less known than his advice in the Diluculum, Erasmus strictly avoided night work and advised his readers to do the same.