There is no reason why someone who is in doubt about the existence of God should not pray for help and guidance on this topic as in other matters. Some find something comic in the idea of an agnostic praying to a God whose existence he doubts. It is surely no more unreasonable than the act of a man adrift in the ocean, trapped if a cave, or stranded on a mountainside, who cries for help though he may never be heard or fires a signal which may never be seen.

The Five Ways fail principally because it is much more difficult than at first appears to separate them from their background in medieval cosmology. Any contemporary cosmological argument would have to be much more different from the arguments of Aquinas than scholastic modernizations customarily are.

The predicate of a sentence may tell you what kind of a thing something is, or how big it is, or where it is, or what is happening to it, and so on. We may say, for instance, of St Thomas Aquinas that he was a human being, and that he was fat, clever, and holier than Abelard; that he lived in Paris in the thirteenth century, that he sat when lecturing, wore the Dominican habit, wrote eight million words, and was eventuarlly poisoned by Charles of Anjou. The predicats we use in saying these things belong, Aristotle would say, in different categories: they belong in the categories of, respectively, substance, quantity, quality, relation, place, time, posture, vesture, action, and passion.

Philosophy is not a matter of knowledge; it is a matter of understanding, that is to say, of organizing what is known.