Modernly known as In honorem sanctae crucis, this work on the holy cross by Rabanus Maurus (a.k.a. Hrabanus Maurus) was completed by 814 and through the manuscript and early printing era it was known under the title of De Laudibus sancte Crucis. The New Westminster Dictionary of Church History says that “with this work Hrabanus paved the way to fill the theoretical gap left open by the previous debates in the East and West about the legitimacy of visual images.”
And visual this work certainly is: It contains 30 carmina figurata (2 unnumbered and 28 numbered) glorifying the holy cross and two xylographic illustrations. The cataloguer at the Pierpont Morgan Library writes that the “Illustrations (pattern or figure poems) are in red and black, sometimes complete woodcuts, sometimes woodcut with letterpress. Various poetic texts can be derived from the resulting configurations. Explanatory text and a transcript of the poem complements each illustration.” The archbishop's work ranks among the earliest examples of printed concrete poetry. And, because his poems are encrypted in a grid of 36 lines each containing 36 letters, this also is an early work in the field of cryptology.