Every man is either a fool or a physician after thirty years of age.

The saying argues that by about thirty, a person should have gained enough experience to understand basic care of their own body and health. Someone who has not learned from ordinary life is sharply, and humorously, labeled a fool.

“Physician” does not necessarily claim professional medical training. It presents practical self-knowledge as the sensible alternative: maturity should bring some ability to recognize one’s habits and limits, not an ability to self-diagnose or replace qualified medical care.

Use it as a wry, admonishing remark about adults learning from experience, especially in everyday self-care. Its absolute wording and dated, potentially exclusionary use of “man” can sound judgmental; reserve it for reflective or humorous contexts, not serious medical advice.