Conversation so far:
Was Le Corbusier a painter before Le Corbusier went into architecture?
Le Corbusier moved to Paris definitively in 1917 and began his own architectural practice with his cousin.
Did he exhibit with famous members of the Cubist movement?
Ozenfant encouraged him to paint, and the two began a period of collaboration.
Rejecting Cubism.
DId he produce any famous paintings after rejecting Cubism?
Rejecting Cubism as irrational and "romantic", the pair jointly published their manifesto, Apres le cubisme and established a new artistic movement, Purism.

Question: How did Le Corbusier know Ozefant?
Self-contained rewrite: How did Le Corbusier know Ozefant?