This description of the contents of the Speculum Naturale is based on the latest version of this speculum, the Douai version. For the contents of the older versions, see the page A genesis of the Speculum Naturale.
In 33 books, the Speculum Naturale describes nature in all its beauty. From a medieval point of view, it is logical that Vincent of Beauvais bases this on the creation story from the first two chapters of the biblical book Genesis.
Like the other specula, the first book of the Speculum Naturale contains the Libellus Apologeticus, the apologetic introduction to the whole Speculum Maius. Vincent of Beauvais here explains in detail the basic principles of the Speculum Maius and offers a justification and defence of his content choices. This Libellus ends - like in the other specula - with a short prologue that deals specifically with the content of the speculum in question, here the Speculum Naturale. This is followed, as in the other specula, by the table of contents of the specific speculum, here again, the Speculum Naturale.
The proper text of the Speculum Naturale then begins in Book II. Following the first sentence from Genesis I, Vincent of Beauvais starts with an account of the creation of the world and then first of all of God himself, Creator of heaven and earth. He then discusses the archetypal world as prefigured from eternity. Next, this second book discusses the "prima materia" (‘first matter’) and the angels, both of which were created before the first day.
Book III discusses the sensory world, as well as the work of the first day: the creation of light and the separation of light and darkness, as well as the Devil and demons.
Book IV deals with the works of the second day, namely the creation of the firmament and the heavens, after which book V treats the other parts of the world that are in the higher regions, namely the ether, the skies and the influences they exert on the under moon.
From books VI to IX, Vincent of Beauvais discusses the first work of the third day of creation, namely the collection of the waters and the nature of water and its many manifestations (VI). This is followed by the uncovering of the earth, the nature of the earth and its properties and species (VII), after which the various minerals, metals and natural colours are discussed (VIII). Finally, book IX covers the many types of stones, both common and precious.
Vincent devotes books X to XV to the second work of the third day of creation, namely the fertilization of the earth. He first presents a general introduction to plants after which the common herbs are discussed (X). Books XI and XII discuss the other cultivated herbs as well as that which is produced by herbs, such as seeds, grains and juices. After herbs, the next three books are devoted to trees. Book XIII first discusses trees in general and then continues with the trees that can be found fairly commonly in the landscape (XIII). Cultivated trees and fruit trees are discussed in book XIV. Finally, an explanation of tree fruits and their juices follows in XV.
Book XVI is devoted to the work of the fourth day, the creation of the heavenly bodies, the signs in the sky and the different times and special days in the astrological year.
Vincent of Beauvais continues following the creation story by describing the results of the work of the fifth day: in book XVII the birds, and in book XVIII the fish.
From book XIX on, the description of the work of the sixth day, namely the creation of the land animals, begins. First, he discusses the beasts of burden (XIX), then the wild animals (XX), and finally the other animals, such as snakes and insects (XXI). Following on from this species description, Vincent of Beauvais adds an analysis of animal nature and an explanation of the different parts of the animal body in book XXII, to continue in book XXIII with a discussion of animal food, the movement and reproduction of animals and their bodily fluids.
This is now followed by a large number of books, from XXIV to XXXIII, on what was, in the eyes of medieval scholars, the most important achievement of the sixth day: the creation of man. First Vincent starts with a very elaborate description of the human mind (XXIV-XXVIII), after which book XXIX deals with the parts of the human body. After this, Vincent seems to conclude in book XXX with a description of the universe and God's rest on the seventh day of creation. Book XXXI then discusses the institution of human nature, man's first state, then the Fall and man's nature after the Fall.
This seems to complete the Speculum Naturale in terms of content, yet Vincent of Beauvais adds two concluding books. In book XXXII, he elaborates on human reproduction and all kinds of natural phenomena in humans, to conclude with the diversity of human beings.
Specific to both the Speculum Naturale and the Speculum Historiale is that Vincent of Beauvais added, to both, a summary of one or more other specula. It is this summary that we find here as the last book in the Speculum Naturale (XXXIII). After describing the places in the world habitable to humankind, there follows a description of human history according to the succession of generations. Here we find a miniature version of the Speculum Historiale.