"It would be better, I think, for the man who really seeks the truth not to ask what the poets say; rather, he should first learn the method of finding the scientific premises that I discussed in the second book; then he should train and exercise himself in this method; and when his training is sufficiently advanced, then, as he approaches each particular problem, he should enquire into the premise needed for proving it, which premise he should take from simple sense-perception, which from experience, whether drawn from life or from the arts, which from the truths clearly apprehended by the mind, in order to draw out from them the desired conclusion."

“Diogenes compared them to fig-trees growing over precipices; for their fruit was devoured by daws and crows, not by men.”

“Employment is Nature's physician, and is essential to human happiness.”

“The fact is that those who are enslaved to their sects are not merely devoid of all sound knowledge, but they will not even stop to learn!”

“Diogenes the Cynic, it is related, was mighty of all people in regard to everything from self-control to endurance. He indulged in sexual lusts, not associating it with pleasure, an attractive good thing to some, but because of the harm that the retention of semen would cause if he avoided the habit of releasing it. When a prostitute who promised to visit him was delayed for some time, he rubbed his genitals with his hand, ejecting semen. After the whore arrived, he sent her away, saying: "my hand celebrated the wedding-hymn first." But it is clearly correct that, likewise, the disciplined man does not on account of pleasure indulge in lusts, but in order to relieve the hindrance acting as if this was not associated with pleasure.”

“Diogenes received an invitation to dine with one whose house was splendidly furnished, in the highest order and taste, and nothing therein wanting. Diogenes, hawking, and as if about to spit, looked in all directions, and finding nothing adapted thereto, spat right in the face of the master. He, indignant, asked why he did so? "Because," Diogenes, "I saw nothing so dirty and filthy in all your house. For the walls were covered with pictures, the floors of the most precious tessellated character — and ranged with the various images of gods, and other ornamental figures.”

“A god, as I have said, commanded me to tell the first use also, and he himself knows that I have shrunk from its obscurity. He knows too that not only here but also in many other places in these commentaries, if it depended on me, I would omit demonstrations requiring astronomy, geometry, music, or any other logical discipline, lest my books should be held in utter detestation by physicians. For truly on countless occasions throughout my life I have had this experience; persons for a time talk pleasantly with me because of my work among the sick, in which they think me very well trained, but when they learn later on that I am also trained in mathematics, they avoid me for the most part and are no longer at all glad to be with me. Accordingly, I am always wary of touching on such subjects, and in this case it is only in obedience to the command of a divinity, as I have said, that I have used the theorems of geometry”