The big question of our time is not Can it be built? but Should it be built? This places us in an unusual historical moment: our future prosperity depends on the quality of our collective imaginations.

Meritocracy is a good thing. Whenever possibly, people should be judged based on their work and results, not superficial qualities.

In my first start-up, I had an initial advertising budget of $5 per day total. That would buy us 100 clicks per day. At $5 per day, marketing people scoffed and said that is too small to matter. But if you think about it, to an engineer, 100 real humans everyday giving your product a try means you can really start improving.

Don’t be in a rush to get big. Be in a rush to have a great product.

Zero invites imagination, but small numbers invite questions about whether large numbers will ever materialize.

The goal of a startup is to figure out the right thing to build-the thing customers want and will pay for-as quickly as possible. In other words, the Lean Startup is a new way of looking at the development of innovative new products that emphasizes fast iteration and customer insight, a huge vision, and great ambition, all at the same time.

When blame inevitably arises, the most senior people in the room should repeat this mantra: if a mistake happens, shame on us for making it so easy to make that mistake.