Not as a quote, but as a line in the context of the book, "They tried to kill my son" repeated over and over was a great illustration of a rational, quite staid man fighting a building rage and becoming something different.
It also served to humanise the Duke right before the tooth scene, building an empathetic connection to make us care about that scene more.
A deceptively simple line used incredibly well.
For pure quotage "It is by will alone I set my mind in motion".