How was Guerilla Marketing born?

When Jay Conrad Levinson who is known as the father of Guerilla Marketing faced with this question in a marketing course: "what are the low cost marketing strageies for small companies?" He said that he would provide the resources related with this subject in the following courses. But he could not find an adequate resource related with and written to date, and he wanted to create one. This is how Guerilla Marketing has come out.