“There is an enormous difference between starting a company and running one. Thinking up great ideas, which requires mainly intelligence and knowledge, is much easier than building an organization, which also requires measures of tenacity, discipline, and understanding. Part of the reason that nineteen out of twenty high-tech start-ups end in failure must be the difficulty of making this critical transition from a bunch of guys in a rented office to a larger bunch of guys in a rented office with customers to serve. Customers? What are those?”