In the book Drive: The Surprising Truth About What Motivates Us by Daniel Pink, which is backed up by several published academic studies, purpose is one of the driving factors of what motivates us in life. There is a shift taking place in workplace as it relates to motivating employees to improve productivity. Our industrial era management thinking says that placing a proverbial carrot (bonus, fear, or other monetary pain/pleasure) was effective when the labor required no cognitive thought (assembly line work), but as the nature of work in the majority of western countries evolve into positions requiring cognitive thought processes, the concept of the carrot provides worse results.
What Pink speaks about, which can be seen at TED, as well as animated at RSA, is that we are motivated by purpose, autonomy and mastery. This welcome memo to all new employees at Apple is an excellent example to reinforcing the culture of purpose.