The most prudent thing any intelligent animal can do, if it would prefer its descendents not to spend a lot of time on a slab with electrodes clamped to their brains or sticking mines on the bottom of ships, or being patronised by zoologists, is to make bloody certain humans don't find out about it.
Pyramids: (Discworld Novel 7) (ed. Random House, 2008) - ISBN: 9781407034669