Holy Spirit
Madeleine L'Engle in The Irrational Season (1977), beginning of Chapter 9 (on Pentecost):
"The Holy Spirit, the third person of the Trinity, is the easiest of this not-at-all-easy concept for me to understand. Any artist, great or small, knows moments when something more than he takes over, and he moves into a kind of 'overdrive,' where he works as ordinarily he cannot work. When he is through, there is a sense of exhilaration, exhaustion, and joy. All our best work comes in this fashion, and it is humbling and exciting.
After A Wrinkle in Time was finally published, it was pointed out to me that the villain, a naked disembodied brain, was called 'It' because It stands for Intellectual truth as opposed to a truth which involves the whole of us, heart as well as mind. That acronym had never occurred to me. I chose the name It intuitively, because an IT does not have a heart or soul. And I did not understand consciously at the time of writing that the intellect, when it is not informed by the heart, is evil."