From Paul Graham’s recent post on Black Swan Farming:

The first time Peter Thiel spoke at YC he drew a Venn diagram that illustrates the situation perfectly. He drew two intersecting circles, one labelled “seems like a bad idea” and the other “is a good idea.” The intersection is the sweet spot for startups.

This concept is a simple one and yet seeing it as a Venn diagram is illuminating. It reminds you that there is an intersectionβ€”that there are good ideas that seem bad. It also reminds you that the vast majority of ideas that seem bad are bad.