Henry - here is what a lifetime of experience has taught me.

1) If we take a step forward, we go forward.

2) If we fart, the gas goes backwards.

3) On BBC Breakfast television, the pretty lady sat on the couch never uncrosses her legs in a way that gives me a sneaky look at her panties.

These truths we take to be self evident.

The insights provided by common sense and experience absolve us from doubting everything.