Conversation so far:
when did Le Corbusier start painting?
CANNOTANSWER.
what happened between 1918-1922?
Le Corbusier moved to Paris definitively in 1917 and began his own architectural practice with his cousin.
what is the name of his cousin?
Pierre Jeanneret .
what kind of architectures did they design?
Between 1918 and 1922, Le Corbusier did not build anything.

Question: what was cubism?
Self-contained rewrite: What was cubism?