Fisher's 'scuttlebutt' method — learning about a company by talking to customers, suppliers, competitors, and former employees — defined qualitative analysis. His 15-point checklist for evaluating a growth company remains one of the best ever created. Buffett says he's '85% Graham and 15% Fisher,' but that 15% is what turned him from a cigar-butt picker into a great-company buyer.

The case for it, the case against, and the rest of the canon open with Pro.