There was a study done in the early 20th century of all the entrepreneurs who entered the automobile industry around the same time as Henry Ford; there were something like 500 automotive companies that got funded, had the internal combustion engine, had the technology, and had the vision. Sixty percent of them folded within a couple of years.

The grim reality is that most start-ups fail. Most new products are not successful. Yet the story of perseverance, creative genius, and hard work persists.

Entrepreneurs can't forecast accurately, because they are trying something fundamentally new. So they will often be laughably behind plan - and on the brink of success.

We must learn what customers really want, not what they say they want or what we think they should want.

This is one of the most important lessons of the scientific method: if you cannot fail, you cannot learn.

The lean startup method is not about cost, it is about speed.

It doesn't matter if you call it a boom or a bubble. The startup business moves in cycles, and what goes up will eventually come down.