4. David Sarnoff: a. Proved that demand creates supply when, after World War II he reintroduced television sets to get money from the veterans who had lots of cash. b. Proved Say's Law by paying people to produce television sets Plus, before Sarnoff, people were not fully "able" to buy a television. c. Invented the concept of the "invisible hand" in 1946. d. Proved Say's Law when he increased the supply of televisions to meet the growing demand