A man should remind himself that an object of faith is not scientifically demonstrable, lest presuming to demonstrate what is of faith, he should produce inconclusive reasons and offer occasion for unbelievers to scoff at a faith based on such ground.
Thomas AquinasIt is possible to demonstrate God's existence, although not a priori, yet a posteriori from some work of His more surely known to us.
Thomas AquinasLikewise grace and glory are referred to the same genus, since grace is nothing other than a certain first beginning of glory in us.
Thomas Aquinas