Book excerpt: Aaron's Code tells the story of the first profound connection between art and computer technology. Here is the work of Harold Cohen - the renowned abstract painter who, at the height of a celebrated career in the late 1960's, abandoned the international scene of museums and galleries and sequestered himself with the most powerful computers he could get his hands on. What emerged from his long years of solitary struggle is an elaborate computer program that makes drawings autonomously, without human intervention - an electronic apprentice and alter ego called Aaron.