preserves and records the judgments formed. Men and animals perceive particulars by means of sense; man attains the knowledge of universals by means of reason. The _`aql_ or rational soul of man is conscious of its own faculties, not by means of an external, i.e., bodily sense, but immediately by the exercise of its own reasoning power. This proves to be an independent entity, even though accidentally connected with a body and dependent on that body for sense perception: the possibility of direct knowledge without sense perception shows that it is not essentially dependent on the body, and the possibility of its existence without the body, which follows logically from its independence, is the proof of its immortality. Every living creature perceives that it has only one _ego_ or soul in itself, and this soul, says Ibn Sina, did not exist prior to the body but was created, that is to say, proceeded by emanation from the Agent Intellect at the time when the body was generated. (_Najat_, p. 51). Under the head of Physics Ibn Sina considers the forces observed in nature, including all that are in the soul, save only that which is peculiar to the rational soul of man. These forces are of three kinds: some, such as weight, are an essential part of the body in which they occur; others are external to the body on which they act, and are such as cause movement or rest; and others, again, are such as the faculties possessed by the non-rational souls of the spheres, which produce movement directly without external impulse. No force is infinite; it may be increased or diminished, and always produces a finite result. Time is regarded as essentially dependent on movement; although it is not itself a form of movement, so far as the idea of time is concerned, it is measured and made known by the movements of the heavenly bodies. Following al-Kindi place is defined as “the limit of the container which touches the contained.” Vacuum is “only a name”, in fact it is impossible, for all space can be increased, diminished, or divided into parts, and so must contain something capable of increase, etc.