O sleepers! what a thing is slumber! Sleep resembles death. Ah, why then dost thou not work in such wise as that after death thou mayst retain a resemblance to perfect life, when, during life, thou art in sleep so like to the hapless dead?
The Notebooks of Leonardo da Vinci (Richter, 1888) - XIX Philosophical Maxims. Morals. Polemics and Speculations.