If we do not know who the customer is, we do not know what quality is.

Nowadays people talk about PayPal's founders as prescient geniuses who would inevitably change the world. It was, however, not so obvious that PayPal would taste its first major success by helping people sell Beanie Babies on eBay. But they had a vision, a hope, and the perseverance to try multiple iterations until they got it right.

By the time that product is ready to be distributed widely, it will already have established customers.

If you cannot fail, you cannot learn.

I would say, as an entrepreneur everything you do - every action you take in product development, in marketing, every conversation you have, everything you do - is an experiment. If you can conceptualize your work not as building features, not as launching campaigns, but as running experiments, you can get radically more done with less effort.

A head start is rarely large enough to matter, and time spent in stealth mode-away from customers-is unlikely to provide a head start. The only way to win is to learn faster than anyone else.

You know how people always talk about how vision is the key to entrepreneurship and perseverance and really seeing what other people don't see? We can actually redeem a fair amount of that folk wisdom.