Long walks on the beach are the supposed holy grail of a romantic evening. The beach becomes a kind of utopia - the place where all our dreams come true.

You could claim that moving from pixelated perception, where the robot looks at sensor data, to understanding and predicting the environment is a Holy Grail of artificial intelligence.

Discretionary effort is the holy grail of employee engagement. The "going above and beyond" drives business valuation.

When I was a boy, I would read those postcards and know exactly why my father was doing what he was doing: he was taking a stab at greatness, that is, if greatness is simply another word for doing something different from what you were already doing--or maybe greatness is the thing we want to have so that other people will want to have us, or maybe greatness is merely the grail for our unhappy, striving selves, the thing we think we need but don't and can't get anyway.