These early years, during which he became acquainted with Louis Guilloux, Edmond Lambert and Max Jacob, are documented in his autobiographical novel Les grèves (1957).
In 1922 Grenier gained a teaching qualification in philosophy and began his academic career at the Institut français in Naples, alongside Henri Bosco.
He then spent some time working on the literary journal La Nouvelle Revue française (NRF) before returning to teaching as a professor of philosophy in Algiers, the capital of Algeria.
Strongly influenced by Les Îles, which came out in 1933, Camus dedicated his first book to Grenier: L'envers et l'endroit, published in Algeria by Edmond Charlot.
While Camus was drawn to rebellion, despite his criticism of violent revolution in L'Homme revolte, and ultimately the desperate cries of La Chute, Grenier was more contemplative, adopting the Taoist principle of wu wei and surreptitiously practising a quietist version of Christianity.