  Albert’s interest in the natural order concludes with his investigations of the final level of natural beings, the animal kingdom. His Treatise on Animals (De animalibus) involves Aristotle’s studies of animals as well as material taken from Thomas of Cantimpré’s encyclopedic On the Nature of Things (De natura rerum). But Albert inserts his own studies of animals into the treatise. He investigates the causes of the properties of different kinds of animals based on their operations and powers. Again, Albert organizes a kind of dictionary of animals based on their various species, listed in alphabetical order as he had done in the other special sciences.