Since Bergson's lectures were never published, and his papers were destroyed after his death, we have nothing save the title of his lectures. The Stanford Encyclopedia of Philosophy explains: "Unfortunately, Bergson had written a will during the 1930s which instructed that all of his papers be destroyed. His wife apparently obeyed this order, throwing all of her husband's papers into the fireplace. There is a rumor that she destroyed a half-written manuscript. The result of this destruction is that the Bergson Archives in Paris (stored at Librairie Jacques Doucet on the Place de Panthéon in Paris) contain only Bergson's personal library." (http://plato.stanford.edu/entries/bergson/)