The "Cyberiad" is an incredibly great introduction too. For example, it contains an electric bard which produces a long poem about tensor algebra, starting with:

> Come, let us hasten to a higher plane > Where dyads tread the fairy fields of Venn, > Their indices bedecked from one to n > Commingled in an endless Markov chain!

The whole thing is here: http://www.aleph.se/Trans/Cultural/Art/tensor.html

Needless to say, Michael Kandel's translation is also hugely impressive.