Body as such is at rest and is not capable of action. To act it needs an agent. Hence it needs an agency to compose its parts and hold them together. We call this agency Nature. Man's body also grows, is nourished and propagates its kind as do plants. This likewise must have its non-corporeal cause. This we call vegetative soul. Man has also sense perception and local motion like the animals. The principle or substance causing this is the animal soul. Man also thinks and reasons and reflects. This is brought about by the rational soul. Finally, man has a still higher function than discursive thought. The latter has to search and to pass from premise to conclusion, whereas the apprehension of the intelligence takes place "without seeking, without effort, and without any other cause except its own essence, because it is full of perfection." In other words, it is immediate intellectual intuition of which Gabirol speaks here. The Intelligence is capable of this because it has in itself, constituting its essence, all the forms of existence, and knowledge means possession of the forms of the things known.
As man is typical of the universe, it follows that there are cosmic existences corresponding to the principles or powers just enumerated in man, and the relation of the latter to the former is that of the particular to the general. Hence there is a cosmic Intelligence, a cosmic soul embracing the rational, the animal and the vegetative parts, and a cosmic nature. Of these the more perfect is the cause of the less perfect; hence the order in which we named them represents the order of causation or of emanation from the prime source.
The lowest of these emanations is the matter which sustains extension or magnitude, and with it the process ceases. This matter is no longer the source of an additional form of existence. The various qualities and attributes which inhere in this corporeal matter are caused by the spiritual substances above. For like the prototype of all generosity and goodness the First Essence or God, every one of the spiritual substances proceeding from him has the same tendency of imparting its form or forms to the substance next below it. But the forms thus bestowed are no longer the same as they are in the essence of the bestowing substance, as it depends upon the recipient what sort of form it will receive. An inferior receiving substance will receive a superior form in an inferior way. That is, the form which in the substance above the one in question is contained in a spiritual and unitary manner, will be transformed in the substance below it into something less spiritual, less unified, and more nearly corporeal, _i. e._, visible and tangible. Hence the visible and tangible, and in general the sensible qualities of particular things in the sublunar world, are in reality descended from a line of spiritual ancestors in the forms of the simple substances, Intelligence, Soul and Nature. But it is their distance from the prime source, which increases with every transmission of influence, together with the cruder nature of the receiving substance, that makes the resulting forms corporeal and sensible. The matter may be made clear if we use the analogy of light, which is invisible as long as it is in air because it penetrates it, but becomes visible when it comes in contact with a gross body which it cannot penetrate. It then remains on the surface condensed, and becomes visible to the senses.