Cat-Ideas and Mouse-Ideas. We can never get rid of mouse-ideas completely, they keep turning up again and again, and nibble, nibble-no matter how often we drive them off. The best way to keep them down is to have a few good strong cat-ideas which will embrace them and ensure their not reappearing till they do so in another shape.

The Note-books of Samuel Butler: Easyread Large Edition (ed. 2008)