"Things that try to look like things often do look more like things than things."
It just so happened that the person who introduced me to Discworld started me off on the Witches books, and given that I was about 13 at the time they were pretty formative years. As a result a decent chunk of my personality is based on a weird combo of the three, Granny Weatherwax in particular, and you'll often find me ranting that I "don't hold with" or "can't be having with" something despite not in fact being an elderly Lancashire woman myself.
For some reason that quote from Wyrd Sisters is just the first one that I remember remembering, if that makes sense? Like the first one I would just quote in relevant situations as a teenager. It's not super deep or special to me beyond that, but I'll always remember it and those early days of discovering the series. Just super nostalgic.