Vincent's Speculum Majus ('The Great Mirror'), the compendium of all the knowledge of the Middle Ages, seems to have consisted of three parts, the Speculum Naturale, Speculum Doctrinale and Speculum Historiale. All the printed editions, however, include a fourth part, the Speculum Morale, added in the 14th century and mainly compiled from Thomas Aquinas, Stephen de Bourbon, and a few other contemporary writers.
The vast tome of the Speculum Naturale ("Mirror of Nature'), divided into thirty-two books and 3718 chapters, is a summary of all the science and natural history known to western Europe towards the middle of the I3th century, a mosaic of quotations from Latin, Greek, Arabic, and even Hebrew authors, with the sources given. Vincent distinguishes, however, his own remarks.
The Speculum Naturale deals with its subjects in the order that they were created: it is essentially a gigantic commentary on Genesis i. Thus book i. opens with an account of the Trinity and its relation to creation; then follows a similar series of chapters about angels, their attributes, powers, orders, &c., down to such minute points as their methods of communicating thought, on which matter the author decides, in his own person, that they have a kind of intelligible speech, and that with angels to think and to speak are not the same process.
Book ii. treats of the created world, of light, color, the four elements, Lucifer and his fallen angels and the work of the first day.
Books iii. and iv. deal with the phenomena of the heavens and of time, which is measured by the motions of the heavenly bodies, with the sky and all its wonders, fire, rain, thunder, dew, winds, &c.
Books v - xiv. treat of the sea and the dry land: they discourse of the seas, the ocean and the great rivers, agricultural operations, metals, precious stones, plants, herbs, with their seeds, grains and juices, trees wild and cultivated, their fruits and their saps. Under each species, where possible, Vincent gives a chapter on its use in medicine, and he adopts for the most part an alphabetical arrangement. In book vi. c. 7 he incidentally discusses what would become of a stone if it were dropped down a hole, pierced right through the earth, and, curiously enough, decides that it would stay in the centre. In book ix he gives an early instance of the use of the magnet in navigation. Book xv. deals with astronomy: the moon, stars, and the zodiac, the sun, the planets, the seasons and the calendar.
Books xvi. and xvii. treat of fowls and fishes, mainly in alphabetical order and with reference to their medical qualities.
Books xviii.-xxii. deal in a similar way with domesticated and wild animals, including the dog, serpents, bees and insects; they also include a general treatise on animal physiology spread over books xxi.-xxii.
Books xxiii.-xxviii. discuss the psychology, physiology and anatomy of man, the five senses and their organs, sleep, dreams, ecstasy, memory, reason, &c.
The remaining four books seem more or less supplementary; the last (xxxii.) is a summary of geography and history down to the year 1250, when the book seems to have been given to the world, perhaps along with the Speculum Historiale and possibly an earlier form of the Speculum Doctrinale.
The second part, Speculum Doctrinale ("Mirror of Doctrine'), in seventeen books and 2374 chapters, is intended to be a practical manual for the student and the official alike; and, to fulfil this object, it treats of the mechanic arts of life as well as the subtleties of the scholar, the duties of the prince and the tactics of the general.It is a summary of all the scholastic knowledge of the age and does not confine itself to natural history. It treats of logic, rhetoric, poetry, geometry, astronomy, the human instincts and passions, education, the industrial and mechanical arts, anatomy, surgery and medicine, jurisprudence and the administration of justice.
The first book, after defining philosophy, &c., gives a long Latin vocabulary of some 6000 or 7000 words. Grammar, logic, rhetoric and poetry are discussed in books ii. and iii., the latter including several well-known fables, such as the lion and the mouse. Book iv. treats of the virtues, each of which has two chapters of quotations allotted to it, one in prose and the other in verse. Book v. is of a somewhat similar nature. With book vi. we enter on the practical part of the work: it gives directions for building, gardening, sowing and reaping, rearing cattle and tending vineyards; it includes also a kind of agricultural almanac for each month in the year.
Books vii.-ix. have reference to the political arts: they contain rules for the education of a prince and a summary of the forms, terms and statutes of canonical, civil and criminal law. Book xi. is devoted to the mechanical arts, of weavers, smiths, armourers, merchants, hunters, and even the general and the sailor.
Books xii.-xiv. deal with medicine both in practice and in theory: they contain practical rules for the preservation of health according to the four seasons of the year, and treat of various diseases from fever to gout.
Book xv. deals with physics and may be regarded as a summary of the Speculum Naturale. Book xvi. is given up to mathematics, under which head are included music, geometry, astronomy, astrology, weights and measures, and metaphysics. It is noteworthy that in this book Vincent shows a knowledge of the Arabic numerals, though he does not call them by this name. With him the unit is termed "digitus"; when multiplied by ten it becomes the "articulus"; while the combination of the articulus and the digitus is the " numerus compositus." In his chapter xvi. 9, he clearly explains how the value of a number increases tenfold with every place it is moved to the left. He is even acquainted with the later invention of the cifra or cipher.
Other works of Vincent of Beauvais are: De eruditione filiorum regalium ('On the education of princes') and a "Tractatus consolatorius de morte amici" ('Consolation up[on the death of a friend'), addressed to Louis on the death of one of his sons in 1260.
This article is largely based on the 1911 Encyclopaedia Britannica'' and should be revised and expanded as required.