Aquinas’ via negativa is well-known. We cannot say what God is, only what he is not. Aquinas is also notorious for his Five Ways. Aquinas seeks to prove the existence of God, claims to have done so, yet also says that God’s nature cannot be known. This seems to be mistaken, however. If one claims to have knowledge that a being or thing exists, then it necessarily follows that one must also have at least some knowledge about that being or thing’s essence. If you claim that X exists, you must have at least some concept of what X is, otherwise you could not claim that X exists, since knowledge of X’s existence includes a minimum amount of knowledge about what X is. One might say that this is only true for things in the universe (contingent), and that God is an exception (necessary), yet this only makes God even more estranged from the universe, making it seem that a deist belief is as far as one can go before stretching beyond the realms of evidence or logic.