An explanation of rhe Total Perspective Vortex, by Douglas Adams:

The Universe, as has been observed before, is an unsettlingly big place, a fact which for the sake of a quiet life most people tend to ignore.

Many would happily move to somewhere rather smaller of their own devising, and this is what most beings in fact do.

For instance, in one corner of the Eastern Galactic Arm lies the large forest planet Oglaroon, the entire "intelligent" population of which lives permanently in one fairly small and crowded nut tree. In which tree they are born, live, fall in love, carve tiny speculative articles in the bark on the meaning of life, the futility of death and the importance of birth control, fight a few extremely minor wars, and eventually die strapped to the underside of some of the less accessible outer branches.

In fact the only Oglaroonians who ever leave their tree are those who are hurled out of it for the heinous crime of wondering whether any of the other trees might be capable of supporting life at all, or indeed whether the other trees are anything other than illusions brought on by eating too many Oglanuts.

Exotic though this behaviour may seem, there is no life form in the Galaxy which is not in some way guilty of the same thing, which is why the Total Perspective Vortex is as horrific as it is.

For when you are put into the Vortex you are given just one momentary glimpse of the entire unimaginable infinity of creation, and somewhere in it a tiny little marker, a microscopic dot on a microscopic dot, which says "You are here."

The Total Perspective Vortex derives its picture of the whole Universe on the principle of extrapolated matter analyses.

To explain - since every piece of matter in the Universe is in some way affected by every other piece of matter in the Universe, it is in theory possible to extrapolate the whole of creation - every sun, every planet, their orbits, their composition and their economic and social history from, say, one small piece of fairy cake.

The man who invented the Total Perspective Vortex did so basically in order to annoy his wife.

Trin Tragula - for that was his name - was a dreamer, a thinker, a speculative philosopher or, as his wife would have it, an idiot.

And she would nag him incessantly about the utterly inordinate amount of time he spent staring out into space, or mulling over the mechanics of safety pins, or doing spectrographic analyses of pieces of fairy cake.

"Have some sense of proportion!" she would say, sometimes as often as thirty-eight times in a single day.

And so he built the Total Perspective Vortex - just to show her.

And into one end he plugged the whole of reality as extrapolated from a piece of fairy cake, and into the other end he plugged his wife: so that when he turned it on she saw in one instant the whole infinity of creation and herself in relation to it.

To Trin Tragula's horror, the shock completely annihilated her brain; but to his satisfaction he realized that he had proved conclusively that if life is going to exist in a Universe of this size, then the one thing it cannot afford to have is a sense of proportion.