The best product builders are both ruthlessly self-critical AND filled with positive faith in the product. They have enough faith and belief to fully commit themselves to the creative endeavor. At the same time, they have the strength of character to see clearly how their product is really quite lousy and can be so much better. You have to have a strong character to keep the pressure on. As F. Scott Fitzgerald said, “The test of a first-rate intelligence is the ability to hold two opposed ideas in the mind at the same time, and still retain the ability to function.” Great product people must believe — and be very critical — at the same time.