In his book Universes, Leslie describes a philosophical parable in which an individual survives a firing squad of fifty expert marksmen unscathed.

He offers two explanations for this remarkable event: either it is a fortuitous outcome, to be expected occasionally by pure chance among many thousands of attempted executions by firing squad; or it is intentional.

Francis Collins references this parable in his book The Language of God: A Scientist Presents Evidence for Belief as part of his argument that the Anthropic Principle strongly suggests a Creator with intent.

Leslie has spoken as follows about his life's work: What I have to contribute is some technical defense of the idea that if you had an infinitely rich [universe], it could be explained by reference to its value.

Philosopher Brendan Sweetman commented that the book promotes a "highly speculative, pantheistic theory that is fascinating in its own way, but that will probably convince very few.