Nicholas (of Damascus[358]), in his book "On the Soul," used to say that the division of the soul was not founded on quantity, but on quality, like the division of an art or a science. Indeed, when we consider an extension, we see that the whole is a sum of its parts, and that it increases or diminishes according as a part is added or subtracted. Now it is not in this sense that we attribute parts to the soul; she is not the sum of her parts, because she is neither an extension nor a multitude. The parts of the soul resemble those of an art. There is, however, this difference, that an art is incomplete or imperfect if it lack some part, while every soul is perfect, and while every organism that has not achieved the goal of its nature is an imperfect being. Thus by parts of the soul Nicholas means the different faculties of the organism. Indeed, the organism, and, in general, the animated being, by the mere fact of possessing a soul, possesses several faculties, such as life, feeling, movement, thought, desire, and the cause and principle of all of them is the soul. Those, therefore, who distinguish parts in the soul thereby mean the faculties by which the animated being can produce actualizations, or experience affections. While the soul herself is said to be indivisible, nothing hinders her functions from being divided. The organism, therefore, is divisible, if we introduce within the notion of the soul that of the body; for the vital functions by the soul communicated to the body must thereby necessarily be divided by the diversity of the organs, and it is this division of vital functions that has caused parts to be ascribed to the soul herself. As the soul can be conceived of in two different conditions, according as she lives within herself, or as she declines towards the body,[359] it is only when she declines towards the body that she splits up into parts. When a seed of corn is sowed, and produces an ear, we see in this ear of corn the appearance of parts, though the whole it forms be indivisible,[360] and these indivisible parts themselves later return to an indivisible unity; likewise, when the soul, which by herself is indivisible, finds herself united to the body, parts are seen to appear. We must still examine which are the faculties that the soul develops by herself (intelligence and discursive reason), and which the soul develops by the animal (sensation). This will be the true means of illustrating the difference between these two natures ("beings"), and the necessity of reducing to the soul herself those parts of her "being" which have been enclosed within the parts of the body.[361] B. Jamblichus.[362]