While I may sound obvious, passion for markets and technologies and ultimately for building a business is incredibly important to us as investors. Passion has a clear emotional connotation and I choose that word deliberately. Building a business is an emotional endeavor. It takes blood, sweat and tears and it seems just about impossible to me that one would be able to come out the other side without having had the experience been an emotional one in addition to all the other things like selling to customers, hiring a great team, raising money from venture investors and hopefully building a tremendous amount of value for all stakeholders. Passion can also have a strong mix of (blind) faith and determination.
Entrepreneurs need to be passionate about their businesses to have the best chance of success. Passion is inspiring and contagious to others on the team (and sometimes important even for investors). People (including me) want to work with others that are passionate about what they are doing.
Passion for a business keeps entrepreneurs focused on the potential and constructively working towards maximizing the business as compared to being paralyzed by the risks and obstacles in front of the company. Determination is critical as well and it goes without saying that passion without determination is not going to lead anywhere interesting. I think it is also true that determination without passion probably also has a similar uninteresting outcome.