Part 2: The Nature and Origin of the Mind, God and Ideas

Proposition 11: The first element, which constitutes the actual being of the human mind, is the idea of some particular thing actually existing. Proof: The essence of man (by the Coroll. of the last Prop.) is constituted by certain modes of God's attributes, namely (by 2. Ax. 2), by the modes of thinking, of all which (by 2. Ax. 3) the idea is prior in nature. Corollary: It follows that the human mind is part of the infinite intellect of God.   Proposition 12: Whatsoever comes to pass in the object of the idea, which constitutes the human mind, must be perceived by the human mind, or there will necessarily be an idea in the human mind of the said occurrence. Proof: Whatsoever comes to pass in the object of any idea, the knowledge thereof is necessarily in God (2.9 Coroll.), in so far as he is considered as affected by the idea of the said object, that is (2.11), in so far as he constitutes the mind of anything. Note: This proposition is also evident, and is more clearly to be understood from 2.7., which see.   Proposition 13: The object of the idea constituting the human mind is the body, in other words a certain mode of extension which actually exists, and nothing else. Proof: If the body were not the object of the human mind, the ideas of the modifications of the body would not be in God (2.9. Coroll.) in virtue of his constituting our mind, but in virtue of his constituting the mind of something else; Note: We thus comprehend, not only that the human mind is united to the body, but also the nature of the union between mind and body.

[3] "Animata"

Axiom 1. All bodies are either in motion or at rest. Axiom 2. Everybody is moved sometimes more slowly, sometimes more quickly. LEMMA 1. Bodies are distinguished from one another in respect of motion and rest, quickness and slowness, and not in respect of substance. Proof: The first part of this proposition is, I take it, self—evident. That bodies are not distinguished in respect of substance, is plain both from 1.5 and 1.8 It is brought out still more clearly from 1.15, note. LEMMA 2. All bodies agree in certain respects. Proof: All bodies agree in the fact, that they involve the conception of one and the same attribute (2. Def. 1). LEMMA 3. A body in motion or at rest must be determined to motion or rest by another body, which other body has been determined to motion or rest by a third body, and that third again by a fourth, and so on to infinity. Proof: Bodies are individual things (2. Def. 1), which (Lemma 1) are distinguished one from the other in respect to motion and rest; Corollary: Hence it follows, that a body in motion keeps in motion, until it is determined to a state of rest by some other body. Axiom 1: All modes, wherein one body is affected by another body, follow simultaneously from the nature of the body affected and the body affecting; Axiom 2: When a body in motion impinges on another body at rest, which it is unable to move, it recoils, in order to continue its motion, and the angle made by the line of motion in the recoil and the plane of the body at rest, whereon the moving body has impinged, will be equal to the angle formed by the line of motion of incidence and the same plane. Definition: When any given bodies of the same or different magnitude are compelled by other bodies to remain in contact, or if they be moved at the same or different rates of speed, so that their mutual movements should preserve among themselves a certain fixed relation, we say that such bodies are in union, and that together they compose one body or individual, which is distinguished from other bodies by the fact of this union. Axiom 3: In proportion as the parts of an individual, or a compound body, are in contact over a greater or less superficies, they will with greater or less difficulty admit of being moved from their position. LEMMA 4: If from a body or individual, compounded of several bodies, certain bodies be separated, Proof: Bodies (Lemma 1) are not distinguished in respect of substance: that which constitutes the actuality (formam) of an individual consists (by the last Def.) in a union of bodies; but this union, although there is a continual change of bodies, will (by our hypothesis) be maintained; LEMMA 5: If the parts composing an individual become greater or less, but in such proportion, that they all preserve the same mutual relations of motion and rest, the individual will still preserve its original nature, and its actuality will not be changed. Proof: The same as for the last Lemma. LEMMA 6: If certain bodies composing an individual be compelled to change the motion, which they have in one direction, for motion in another direction, but in such a manner, that they be able to continue their motions and their mutual communication in the same relations as before, the individual will retain its own nature without any change of its actuality. Proof: This proposition is self—evident. LEMMA 7: Furthermore, the individual thus composed preserves its nature, whether it be, as a whole, in motion or at rest, whether it be moved in this or that direction. Proof: This proposition is evident from the definition of an individual prefixed to Lemma 4. Note: We thus see, how a composite individual may be affected in many different ways, and preserve its nature notwithstanding.


1. The human body is composed of a number of individual parts, of diverse nature, each one of which is in itself extremely complex. 2. Of the individual parts composing the human body some are fluid, some soft, some hard. 3. The individual parts composing the human body, and consequently the human body itself, are affected in a variety of ways by external bodies. 4. The human body stands in need for its preservation of a number of other bodies, by which it is continually, so to speak, regenerated. 5. When the fluid part of the human body is determined by an external body to impinge often on another soft part, it changes the surface of the latter, and, as it were, leaves the impression thereupon of the external body which impels it. 6. The human body can move external bodies, and arrange them in a variety of ways. Proposition 14: The human mind is capable of perceiving a great number of things, and is so in proportion as its body is capable of receiving a great number of impressions. Proof: The human body (by Post. iii. and vi.) is affected in very many ways by external bodies, and is capable in very many ways of affecting external bodies. Proposition 15: The idea, which constitutes the actual being of the human mind, is not simple, but compounded of a great number of ideas. Proof: The idea constituting the actual being of the human mind is the idea of the body (2.13), which (Post. 1) is composed of a great number of complex individual parts.