The animal organism, as living generality, is the concept which passes through its three determinations, each of which is in itself the same total identity of substantial unity and, at the same time and as determined for itself by the form, is the transition into others, so that the totality results from this process. It is only as this self-reproducing entity, not as an existing one, that the animal organism is living.
The animal organism is therefore: (a) a simple, general being in itself in its externality, whereby real determinacy is immediately taken up as particularity into the general, and is thereby the unseparated identity of the subject with itself;—sensibility;—(b) particularity, as excitability from the outside and, on the other hand, the countereffect coming from the outward movement of the subject;—irritability;—(c) the unity of these moments, the negative return to itself through the relation of externality, and thereby the generation and positing of itself as an individual,—reproduction. Inwardly, this is the reality and foundation of the first moments, and outwardly, this is the articulation of the organism and its armament.
These three moments of the concept have their reality in three systems, namely, the nervous system, the circulatory system, and the digestive system. The first is in the systems of the bones and sensory apparatus, whereas the second turns outwardly on two sides in the lungs and the muscles. The digestive system is, however, as a system of glands with skin and cellular tissue, immediate, vegetative, reproductive, but as part of the actual system of the intestines it is the mediating reproduction. The animal thus divides itself in the center (insectum) into three systems, the head, thorax, and the abdomen, though, on the other hand, the extremities used for mechanical movement and grasping constitute the moment of the individuality outwardly positing and differentiating itself.
Source of English translation: Georg Wilhelm Friedrich Hegel, Encyclopedia of the Philosophical Sciences in Outline and Critical Writings, edited by Ernst Behler and translated by Steven A. Taubeneck. New York: Continuum Publishing Company, 1990, pp. 48-55, 140-42, 152-56, 181-86.
Reprinted by permission of the Continuum International Publishing Group.