346. (6) The two kinds of forms into which influx operates are plant forms and animal forms. The earth produces only two universal forms, as people know from their acquaintance with the two kingdoms of nature called the animal kingdom and the plant kingdom. They also know that all the constituents of the same one kingdom have much in common. So for example, in constituents of the animal kingdom we find sense organs and motor organs, and members and viscera, which are actuated by brains, hearts and lungs. And in the plant kingdom, its constituents take root in the earth and produce a stem, branches, leaves, flowers, fruits, and seeds. The productions of both the animal kingdom and the plant kingdom into their forms take their origin from the spiritual influx and operation of the sun of heaven where the Lord is, and except for the fixing of their forms, as stated above, not from the influx and operation of nature from its sun. [2] All animals, great and small, take their origin from something spiritual in the lowest degree, which is called natural. The human being alone is a product of all the degrees, of which there are three, called celestial, spiritual and natural. Because every degree of height or discrete degree ranges from its highest level of perfection to its lowest by a continuous succession, as light fades to dark, so also do animals. Consequently there are higher forms, lower forms, and lowest forms of these. Higher animals include elephants, camels, horses, mules, cattle, sheep, goats, and the rest that are animals either of the herd or the flock. Lower animals are birds. And the lowest ones are fish and shellfish, which, being the lowest forms of this degree, live almost in a state of darkness, while the higher live in the light. [3] Nevertheless, because animals have life only from the lowest spiritual degree, called natural, they cannot look in any other direction than to the ground and to their food there, and to others of their kind for the sake of their propagation. The soul in all of these is a natural affection or appetite. It is the same with constituents of the plant kingdom, in which there are higher, lower and lowest forms. The higher forms are fruit trees. Lower forms are grapevines and bushes. And the lowest forms are grasses. Plants, however, take from the spiritual origin from which they spring the characteristic of being forms of service, while animals take from the spiritual origin from which they spring the characteristic of being forms, as we said, of affections and appetites.