Honesty consists not in never stealing but in knowing where to stop in stealing, and how to make good use of what one does steal. It is only great proprietors who can steal well and wisely. A good stealer, a good user of what he takes, is ipso facto a good inventor. Two men can invent after a fashion to one who knows how to make the best use of what has been done already.
— from The Note-Books of Samuel Butler
* with thanks to Austin Kleon