In the immortal words of Monty Python, "Amongst [the Spanish Inquisition's] weaponry are such diverse elements as: fear, surprise, ruthless efficiency, an almost fanatical devotion to the Pope, and nice red uniforms." Truthfully, not a bad formula for startup success. Ok, maybe not devotion to the Pope, per se, but fanatical devotion to your company. That brand of single-mindedness has long been the linchpin of success for entrepreneurs. (As an aside, the business about the nice red uniforms reminds me of a recent lunch I had at Google. My host giddily noted that it would be impossible at this point to collect all the Google shirts that have been printed. While I savor the sort of camaraderie that ubiquitous company swag can promote, I'm afraid it felt a little 1999.)

While the term fanatic is pejorative in many circles, I love fanatics. Fanatics make first class entrepreneurs. As long as I have been working with startups, I have seen the power of fanaticism in action. Entrepreneurs who go to sleep thinking about their companies, wake up thinking about their companies, and often times dream about their companies in the hours in between, are the ones who do everything it takes for their startups to succeed.

It takes a certain kind of fanaticism to win. You must be fanatical about that which your company does, not just about making money. Great entrepreneurs believe that they are changing the world for the better. I recently saw an entrepreneur describe the new toilet her company was building. For her it was about a better bathroom experience; it was about saving water, saving space and being cleaner; and it was about revolutionizing the toilet industry. She’s the kind of entrepreneur who manages to make toilets so compelling that she earns a spot on the same stage as Bill Gates and Steve Jobs at the Wall Street Journal conference.

Similarly, I have a buddy who started a “luxury residence club” called Exclusive Resorts. He eats, breaths and sleeps building a better high end vacation experience (it’s a tough job but somebody’s got to do it). He’s the kind of guy who gets invited to a Warren Buffet seminar and asks a “question” something like: “Hi, I’m the founding CEO of a company called Exclusive Resorts — what advice would you give to an entrepreneur who is trying to create the best possible vacation experience for folks like those in this room?” (Luckily for him, Warren can appreciate that kind of chutzpah and responded with, “first of all, I’d give a commercial for my company in a room full of people like this.”) He’s the kind of guy who is always asking about the best place you’ve vacationed. He’s the kind of guy who is always thinking about his business. And he’s the kind of guy who manages to go from zero to sixty multi-million dollar vacation homes and wins a “Best of the Best” from the Robb Report in his first year of business.

When I invest, I look for the fanatics. They’re the ones who can’t imagine doing anything but the thing they’re doing. They don’t just see the pain in the market, they feel it. Look at Rene Lacerte, the founder of a company called PayCycle in which I invested several years ago. Rene’s grandfather started a payroll company. Rene’s father started a payroll company. It was hardly a question that he too would start a payroll company (particularly after cutting his teeth on payroll at Intuit). And when he did, it was with the sort of fanaticism you would expect from a third generation payroll entrepreneur. Rene and his team will not rest until they have built the best possible payroll service for small business. That is the sort of fanaticism behind which I want to put my money.

Sure, entrepreneurial success is not all about fanaticism. It has a lot to do with smart decisions, excellent hiring, ripe markets and a whole lot of luck. But given all the impediments to success, I’d sure rather start with someone who is fanatical about what he’s doing than otherwise. Fanaticism is the secret weapon… that, and the comfy chair.