Editor's note : When venture capitalists invest in early stage startups, more than anything else they are investing in the founders of the company and their ability to lead their employees through the most improbable set of circumstances to take an idea from a germ to a real and profitable business. In this guest post, Ben Horowitz of VC firm Andreessen Horowitz explains the leadership traits he and his co-founder Marc Andreessen look for before they invest in a startup. Some of their investments include Skype , Zynga , Factual , and RockMelt . Before becoming investing partners, Horowitz and Andreessen co-founded Opsware , which they sold to HP for $1.6 billion, and prior to that Horowitz was an executive at Netscape. At Andreessen Horowitz, we favor founders running the company. The reasons are many (and will be the topic of a future blog post). As a result, we spend a great deal of time thinking about the characteristics required to be a founding CEO. Perhaps the most important attribute required to be a successful founding CEO is leadership. So what is leadership and how do we think about it in the context of the CEO job? Are great leaders born or made? Most people define leadership in the same way that Supreme Court Justice Potter Stewart famously defined pornography when he said: “I know it when I see it.” A better definition comes from former Secretary of State Colin Powell who said: “You have achieved excellence as a leader when people will follow you anywhere if only out of curiosity.” For our purposes, we can generalize this to be the measure of the quality of a leader: the quantity, quality and diversity of people who want to follow her.