Pythagorean concepts bear a resemblance to certain tenets of Freud's ethos as well as to certain of his psychoanalytic formulations which, internal evidence suggests, were in part derived from them. While the factor of independent origin cannot be discounted, Freud's extensive erudition, his great interest in the early Greek thinkers and the internal evidence in his works makes it probable that he was acquainted with the Pythagorean concepts.

The relevant Pythagorean concepts are as follows: the sense of justice, from which are derived the concepts of the equality of mankind, the equality of women, the formation of a high personal and professional ethos, the concepts of a lack of control of the impulses as unjust to the self and to others; and the need to preserve harmony and thus mental and physical health through the exercise of moderation in all things, as well as through a knowledge of the self.