The Cambridge History of English and American Literature in 18 Volumes (1907–21).
Volume II. The End of the Middle Ages.
§ 12. Prose; The Astrolabe
The prose complements are two:—a translation of Boethius’s de Consolatione, executed at an uncertain time but usually associated in general estimate of chronology with Troilus, and a short unfinished Treatise on the Astrolabe (a sort of hand-quadrant or sextant for observing the positions of the stars), compiled from Messahala and Johannes de Sacrobosco, intended for the use of the author’s “little son Lewis,” then (1391) in the tenth year, and calculated for the latitude of Oxford. Both are interesting as showing the endeavour of Middle English prose, in the hands of the greatest of Middle English writers, to deal with different subjects. The interest of the Astrolabe treatise is increased by the constant evidence presented by the poems of the attraction exercised upon Chaucer by the science of astronomy or astrology. This, so long as the astrological extension was admitted, kept its hold on English poets and men of letters as late as Dryden, while remnants of it are seen as late as Coleridge and Scott. It is an excellent piece of exposition—clear, practical and to the purpose; and, in spite of its technical subject, it is, perhaps, the best prose work Chaucer has left us. But, after all, it is a scientific treatise and not a work of literature.