Cicero, de Divinatione 1.30:
“Plato therefore encourages people to go to sleep with their bodies thus disposed that there be nothing which could introduce any wandering from or disturbance of sleep. From which it is thought that the Pythagoreans prohibited the consumption of beans, because that food causes a great flatulence which is contrary to the tranquility of a mind seeking the truth.”
Iubet igitur Plato sic ad somnum proficisci corporibus adfectis, ut nihil sit, quod errorem animis perturbationemque adferat. Ex quo etiam Pythagoreis interdictum putatur, ne faba vescerentur, quod habet infiationem magnam is cibus tranquillitati mentis quaerenti vera contrariam.