Not the Theophilus of the Gospel of Luke, not Theophilus the ancient Greek geographer, not the VIIIth-century astrologer Theophilus of Edessa, not the IXth-century Byzantine emperor, not Theophilus Erotikos the Xth-century geometer — but the Diverse Theophilus is my hero of the moment. He was, I think, a Benedictine monk somewhere in Germany, late XIth or XIIth century, author of De diversis artibus, which I have been reading through the unfortunate distractions of the past week.

I found Theophilus by chance in a second-hand bookstore, where I have found other authors discreetly hiding — in Nelson’s admirable 1961 edition in Latin and English. It is in three sections called “books,” the first about the art of painting in many media, the second for the production of all kinds of glass, and the third with various metals and metal-depending implements, such as church bells and organs. It is an extraordinary conspectus of the arts, written in a century before what we call the Renaissance, in the spirit that would animate the Gothic movement.

Many surviving mediaeval manuals contain hints to artists, but the De diversis is uniquely a full-bore treatise. Yet its author does not mention his name, or anything about himself. From topical references we may deduce his time, place, and religious occupation.

I was myself puzzled by his range, for in everything he precisely indicates workshop arrangements and craft techniques that he must have witnessed to describe, and nowhere does he depart from his practical tone, even when prescribing decorations.

He is a very humble monk, without posture or airs, and in the habit of our long Middle Ages — which was interested in the productions of men, not in the style of their egos. It was the civilization that produced Chartres, not Pringles or the Barbie doll.

But more than this the spirit is compatible with the “diverse arts” of pre-modern India and China. There is no hint of the modern concept of “fine art.” Leonardo might be disappointed to find that painting does not take pride of place above the other arts, nor does Michelangelic sculpture. Each art is rather a component of the whole.

One might also be surprised to find that the methods of oil painting were known long before the Quattrocento, and Cennino Cennini. It is heartbreaking that, through ruthless time, no examples have survived of this or many of the other genres to which Theophilus alludes.