Another Paul Graham gem, Startup = Growth discusses the centre-stage role played by growth in a startup, and how growth is really the only way to measure a startup, be that a founder, investor or competitor.
As Graham nicely puts it, focusing on hitting a growth rate "reduces the otherwise bewilderingly multifarious problem of starting a startup to a single problem". In other words any decisions, be that hiring, expenditure, product development all become easier to make when filed in behind growth. It also keeps the founders and the company moving, forcing them to act not procrastinate.
To put it in perspective, a company that grows at 1% a week 4 years later will be making $7,900 a month. A startup that grows at 5% a week will in 4 years be making $25 million a month.
The article is packed full of other insights and wisdom. Definitely worth a read.