There's a story they tell about St Thomas Aquinas. I don't have a text to hand and I'm probably misremembering but it goes something like this. Late in life he had a direct experience of the Divine. These things are impossible to communicate. If they weren't we'd all be enlightened by word of mouth and the spiritual life would be a doddle- which it isn't. Anyway that didn't stop the brothers from pestering him to tell them what it was that had happened to him. So he sat in his chair- he was a very large man- and he scowled and he ruminated and finally he nodded towards the massed volumes of the Summa Theologica- his life's work- one of the foundation stones of Western philosophy- and said, "Put it this way, if I'd known then what I know now I wouldn't have bothered."