These periods could be used to supplement historical ones where history was not available. He reaffirmed Lubbock's view that the Paleolithic was an age of food gathering and the Neolithic an age of food production. He took a stand on the question of the Mesolithic identifying it with the Epipaleolithic. The Mesolithic was to him "a mere continuance of the Old Stone Age mode of life" between the end of the Pleistocene and the start of the Neolithic. Lubbock's terms "savagery" and "barbarism" do not much appear in "Man Makes Himself" but the sequel, "What Happened in History" (1942), reuses them (attributing them to Morgan, who got them from Lubbock) with an economic significance: savagery for food-gathering and barbarism for Neolithic food production. Civilization begins with the urban revolution of the Bronze Age.