(25) Accordingly, in the larger definitions the number of the species that are discovered are in the ten Categories; and in the least, the principal points of the nearest species being taken, mark the essence and nature of the thing. But the least consists of three, the genus and two essentially necessary species.

(11) We divide, therefore, the genus of what is proposed for consideration into the species contained in it; as, in the case of man, we divide animal, which is the genus, into the species that appear in it, the mortal, and the immortal. And thus, by continually dividing those genera that seem to be compound into the simpler species, we arrive at the point which is the subject of investigation, and which is incapable of further division.

(20) It is best, then, to divide the genus into two, if not into three species.

(16) Now one Division divides that which is divided into species, as a genus; and another into parts, as a whole; and another into accidents.

(46) Among the Placentals , are found the following sub-families: The Edentata , or toothless creatures, such as the sloths, ant-eaters, armadillos, etc.; the Sirena , or sea cows, manatees , dugongs, etc.; the Cetacea , or whales, dolphins, porpoises, etc., which resemble fishes but which are true mammals, bringing forth matured young which are nourished at the breast; the Ungluta , or hoofed animals, such as the horse, the cow, the rhinoceros, the hippopotamus, the pig, the camel, the deer, the sheep, etc.; the Hyracoidea , or family of the coney, rock, rabbit, etc.; the Proboscidea , or trunked animals, such as the elephants; the Carnivora , or flesh-eaters, including the seal, the bear, the dog, the wolf, the lion, the tiger, the leopard, etc. The wolf and similar animals belong to the sub-family of dogs; while the lion, tiger, and similar animals belong to the sub-family of cats; the Rodentia , or gnawers, including the rat, the hare, the beaver, the squirrel, the mouse, etc.; the Insectivora , or insect-feeders, such as the mole, the shrew, the hedgehog, etc.; the Cheiroptera , or wing-fingered animals, including the great families of bats, etc.; the Lemuroidea , or Lemur family, the individuals of which resemble a monkey in general appearance, but have in addition a long bushy tail and a sharp muzzle like a fox—they are like a small fox having hands and feet like a monkey; the Primates , or family of creatures like the monkey, baboon , man-apes, gibbons, gorillas, chimpanzees, orang-outang, and finally, the "connecting links" between the apish forms and Man.

(1) And all dependent from Above are subdivided into species in the fashion which I am to tell. The genera of all things company with their own species; so that the genus is a class in its entirety, the species is part of a genus. The genus of the Gods will, therefore, make the species of the Gods out of itself. In like way, too, the genus of the daimons, and of men, likewise of birds, and of all [animals] the Cosmos doth contain within itself, brings into being species like itself. There is besides a genus other than the animal,—a genus, or indeed a soul, in that it’s not without sensation,—in consequence of which it both finds happiness in suitable conditions, and pines and spoils in adverse ones;—I mean [the class] of all things on the earth which owe their life to the sound state of roots and shoots, of which the various kinds are scattered through the length and breadth of Earth.

(12) For, after dividing "the animal" into mortal and immortal, then into terrestrial and aquatic; and the terrestrial again into those who fly and those who walk; and so dividing the species which is nearest to what is sought, which also contains what is sought, we arrive by division at the simplest species, which contains nothing else, but what is sought alone.

(9) Accordingly we must first take the genus, in which are the points that are nearest those above; and after this the next difference. And the succession of differences, when cut and divided, completes the "What it is." There is no necessity for expressing all the differences of each thing, but those which form the species.