Think of Adam and Eve like an imaginary number

The Cassington Scholar is traditionally given to  a free thinker. It's his function to challenge the faith of the Scholars. Naturally he'd say that. But think of Adam and Eve like an imaginary number, like the square root of minus one: you can never see any concrete proof it exists , but if you include it in your equations, you can calculate all manner of things that couldn't be imagined without it.

P. Pullman, Northern Lights (1995), 372-3