As amazing as the prequel, my most favourite from this book include:


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.