A footnote

During the early twentieth century, smoking clubs were not uncommon for the 'social' use of opium among well-to-do Parisians, and both Picabia and Apollinaire participated in them (conversations with Mme. Buffet-Picabia, October 1962). That practice was apparently more important for Picabia and continued by him until ca. 1918–19.

Efforts by this author to detect an influence of the drug in Picabia's art have failed to isolate any demonstrable feature in either the conception or execution of his paintings.

The effect of opium on artistic creation is largely unexplored.