The evolutionary urge drives man to seek for intenser forms of fulfillment, since his basic urge is for more life, more consciousness, and this contentment has an air of stagnation that the healthy mind rejects. (This recognition lies at the centre of my own 'outsider theory': that there are human beings to whom comfort means nothing, but whose happiness consists in following an obscure inner-drive, an 'appetite for reality'.)

p. 32 - Tree By Tolkien (1974)