Most people know Dorothy Sayers as the author of detective stories based on the character Lord Peter Wimsey. Others know her as a lay theologian in the tradition of G. K. Chesterton and C. S. Lewis. In both careers, she showed great ingenuity in tracking down mysteries.

Sayers's remarkable book The Mind of the Maker follows the trail of perhaps the greatest mystery of all, the Trinity. Although an interest in the Trinity is reviving, the average person in the pew has little comprehension of this doctrine.

We understand God best, Dorothy Sayers suggests, by thinking of him as a creator. Imagine God as an engineer, watchmaker, or immovable force, and you will go off track. God's image reflects from us most clearly in the act of creation.

I apply Sayers's notion to the act of creativity I know best: writing. Every writer begins with an Idea, or an Essence. For instance, I have been thinking about this column for several days, pondering what to say. Finally the time comes to begin writing, and for that I must choose a medium of Expression. I write as an essayist, in this case with a strict limit of 900 words. John Milton expressed theology in an epic poem. John Wesley wrote sermons, his brother hymns.

The Expression changes shape daily. On average, I end up deleting 100 pages from the first draft of every book. As I edit, I realize that some pages distract from the original Idea; they make the book bog down, or go in conflicting directions at once. The Idea has a life of its own, and I have learned to follow instincts alerting me when my Expression misrepresents the Idea. Every human creator seeks to express the Idea perfectly, and ultimately fails.

The act of creation does not end, though, until another person receives the communication. ...