## proof

**Robert Hunt**concludes our Origins of Proof series by asking what a proof really

*is*, and how we know that we've actually found one. One for the philosophers to ponder...

**Jon Walthoe**explains the tricks involved and how great thinkers like Pythagoras, Newton and Gödel tackled the problems.

**J.V. Field**continues our series on the origins of proof with an examination of Kepler's astronomy.