We can judge the heart of a man by his treatment of animals.

Although widely attributed to Immanuel Kant, this aphorism does not match Kant’s characteristic phrasing and is not securely traceable to a specific passage in his published works. The sentiment, however, aligns loosely with a Kantian idea found in his moral writings: cruelty to animals is morally troubling because it can erode a person’s capacity for sympathy and thereby damage duties we owe to human beings. Read in that light, the quote suggests that how someone treats vulnerable, non-reciprocal beings reveals (and shapes) their moral character—habits of callousness in “small” contexts can signal deeper defects in humanity and respect for moral law.