Little Nuggets

The Hitchhikers Guide to the Galaxy offers this definition of the word "Infinite."
Infinite: Bigger than the biggest thing ever and then some. Much bigger than that in fact, really amazingly immense, a totally stunning size, real "wow, that's big," time. Infinity is just so big that, by comparison, bigness itself looks really titchy. Gigantic multiplied by colossal multiplied by staggeringly huge is the sort of concept we're trying to get across here.

It is impossible to import things into an infinite area, there being no outside to import things in from.

See Imports.

It is known that there are an infinite number of worlds, simply because there is an infinite amount of space for them to be in. However, not every one of them is inhabited. Therefore, there must be a finite number of inhabited worlds. Any finite number divided by infinity is as near to nothing as makes no odds, so the average population of all the plantes in the Universe can be said to be zero. From this it follows that the population of the whole Universe is also zero, and that any people you may meet from time to time are merely the products of a deranged imagination.

In fact there are three freely convertible currencies in the Galaxy, but none of them count. The Altarian Dollar has recently collapsed, the Flainian Pobble Bead is only exchangeable for other Flainian Pobble Beads, and the Triganic Pu has its own special problems. Its exchange rate of eight Ningis to one Pu is simple enough, but since a Ningi is a triangular rubber coin six thousand eight hundred miles along each side, no one has ever collected enough to own on Pu. Ningis are not negotiable currency, because the Galactibanks refuse to deal in fiddling small change. From this basic premise it is very simple to prove that the Galactibanks are also the product of a deranged imagination.

The function of art is to hold a mirror up to nature, and there simply isn't a mirror big enough—see point one.

Well, in fact there is an awful lot of this, largely because of the total lack of money, trade, banks, art or anything else that might keep all the nonexistent people of the Universe occupied.
However, it is not worth embarking on a long discussion of it now because it really is terribly complicated. For further information see Guide Chapters seven, nine, ten, eleven, fourteen, sixteen, seventeen, nineteen, twenty-one to eighty-four inclusive, and in fact most of the rest of the Guide.