[W]e didn't do much to alter the course of human history, did we?' said Philip. 'As one old spy to another, I reckon I'd have been more use running a boys' club. Don't know what you feel.'

John le Carré, Silverview

We are what we do, not what we think.  Only the interactions count.

Iain Banks, The Player of Games

Theory is when you know everything but nothing works.

Practice is when everything works but nobody knows why.

Unknown