When the first anthropoid steed erect and picked up a stone to throw at an enemy, man took his first cautious step out of the here and now. The idea that, after it's brief flight trough the air, the stone could knock out the enemy can be seen as the moment when awareness of the future was born. In throwing the stone, man was in a sense catapulting himself out of the realm of birds, animals, and plants. A crucial split occurred in the thrower's head. One part controlled the body and was anchored in the present, just as it had always been, but the other small part unfurled out of the present to a moment just beyond the present, to a possible future event in the world. This evolutionairy process created a new perception of time which was embedded in actual time. This thinking is a fertile soil for melancholy, as well as for melancholic wonderment.

From: Mark Manders, Why Do We Have Time to Think about Our Bodies