“When they retired, they purified their reasoning powers from the noises and perturbations to which they had been exposed during the day, by certain odes and hymns which produced tranquil sleep, and few, but good dreams.” ~ Iamblichus: The Life of Pythagoras or On The Pythagorean Life, Music and Poetry. Taken from The Pythagorean Sourcebook and Library, compiled and translated by Kenneth Sylvan Guthrie, p. 84-85.
