In 1944, Hadot was ordained, but following Pope Pius XII's encyclical Humani generis (1950) left the priesthood.

[10] Wittgenstein had claimed that philosophy was an illness of language and Hadot notes that the cure required a particular type of literary genre.

He identified and analyzed the "spiritual exercises" used in ancient philosophy (influencing the thought of Michel Foucault in the second and third volumes of his History of Sexuality).

The philosophy teacher's discourse could be presented in such a way that the disciple, as auditor, reader, or interlocutor, could make spiritual progress and transform himself within.

"[15] Hadot shows that the key to understanding the original philosophical impulse is to be found in Socrates.

Hadot didn't 'discover' the practice and benefits of 'spiritual exercises' but he 'rediscovered' it and brought it back into modern day philosophical conversation much like previous philosophers did in the past, namely, Erasmus, Montaigne, Descartes, Kant, Emerson, Marx, Nietzsche, William James, Wittgenstein, Jaspers, and Rilke.