But the fact that a sextant will let you navigate accurately across an ocean does not mean that the sun and stars do rotate around us. For all that we have done, as a civilisation, as individuals, the universe is not stable, and nor is any single thing within it. Stars consume themselves, the universe itself rushes apart, and we ourselves are composed of matter in constant flux. Colonies of cells in temporary alliance, replicating and decaying and housed within, an incandescent cloud of electrical impulse and precariously stacked carbon code memory. This is reality, this is self knowledge, and the perception of it will, of course, make you dizzy. Some of you have served in Vacuum Command, and -will no doubt think that out there you have confronted existence vertigo.