That’s according to Jay Walker, the investor-turned-serial entrepreneur who founded Priceline.com in the 1990s.

“Imagination is sort of the great untapped resource,” Walker said at the Fortune Global Forum in Guangzhou, China on Thursday. “We talk about innovation, but there is no innovation without imagination—the moment when we have an original thought.”

Walker is well-qualified to remark on the subject. After creating Priceline in the late 1990s, he left the travel booking site in 2000, shortly after its blockbuster IPO. He went on to launch a weight-loss and nutrition app called foodtweaks and LabTV, an online video platform for medical scientists. His latest venture, Upside Travel, returned him to the travel category; it rewards business travelers with gift cards if they’re flexible in scheduling their flights and hotels. All told, Walker says he’s named on 700 issued or pending U.S. and international patents, which makes him the world’s 11th most patented inventor alive.

So in addition to commenting on the difficulty of harvesting imagination, he also provided insight into how it can—in fact—be fostered.

“What are the characteristics of a society that makes it a fertile place for imagination and innovation?” Alan Murray, chief content officer for Fortune publisher Time Inc, asked Walker in an interview.

It’s about “about rejecting the old,” Walker replied. “It’s about saying, ‘I have a new idea.’ If your idea is, ‘I know everything,’ then you’re not going to innovate. If your idea is, ‘The world has nothing to teach me,’ you’re not going to innovate.”