What’s the best way to retain employees?

Ben Horowitz (Co-Founder & Partner @ Andreessen Horowitz)
Why Startups Should Train Their People – Ben’s Blog

After putting economics, aside, I found that there were two primary reasons why people quit: 1) They hated their manager – generally the employees were appalled by the lack of guidance, career development and feedback they were receiving. 2) They weren’t learning anything – the company wasn’t investing in the employees.