Say “Holy Spirit,” and most imagine a dove or tongues of fire gently descending. But the Celts envisioned something wilder: a goose in flight—honking across the sky, untamed and impossible to ignore.

The Holy Spirit has no face, but he does have a gaze. We can warm to, and benefit from, images of Christ. But remember, these are all creations of the imagination, whether they come from Michelangelo ...