Knowledge is dangerous, which is why governments often clamp down on people who can think thoughts above a certain caliber.

Fantasy is an exercise bicycle for the mind. It might not take you anywhere, but it tones up the muscles that can.

Somewhere around the place I've got an unfinished short story about Schrodinger's Dog; it was mostly moaning about all the attention the cat was getting.

Granny Weatherwax was often angry. She considered it one of her strong points. Genuine anger was one of the world's greatest creative forces. But you had to learn how to control it. That didn't mean you let it trickle away. it meant you dammed it, carefully, let it develop a working head, let it drown whole valleys of the mind and then, just when the whole structure was about to collapse, opened a tiny pipeline at the base and let the iron-hard stream of wrath power the turbines of revenge.

...no-one is finally dead until the ripples they cause in the world die away... The span of someone's life, they say, is only the core of their actual existence.

Unseen University was much bigger on the inside. Thousands of years as the leading establishment of practical magic in a world where dimensions were largely a matter of chance in any case had left it bulging in places where it shouldn't have places. There were rooms containing rooms which, if you entered them, turned out to contain the room you'd started with, which can be a problem if you are in a conga line.

A witch who is bored might do ANYTHING. People said things like 'we had to make our own amusements in those days' as if this signified some kind of moral worth, and perhaps it did, but the last thing you wanted a witch to do was get bored and start making her own amusements, because witches sometimes had famously erratic ideas about what was amusing.