For Bijan Sabet, making the right investment comes down to asking himself four simple questions. Over the years, he’s honed his eye for spotting exceptional founders, which led him to invest in Twitter at the Series B stage, serving on the board from 2008 to 2011, and Tumblr at the Series A, serving on the board from 2007 to 2013.

Bijan spent the first ten years of his career in the startup world. Living in San Francisco during the early days of the consumer internet, he helped build foundational entertainment platforms including WebTV. When he and his wife had their first child, he moved back to Boston to become an Entrepreneur in Residence at Charles River Ventures.

There he met Santo Politi, who was just beginning to think about starting a new venture capital firm. In 2005, Bijan joined Spark as a co-founder with the goal of building a new kind of firm—one that would push back against the traditions, good and bad, of typical venture capital. The approach has helped him identify founders who are fundamentally changing the way people interact with technology. “I find that the entrepreneurs I’m drawn to are willing to take a bigger chance on things,” he says. “It tends to lead to better results in terms of the mission, the purpose, and types of people they can recruit.”