Ethics

by Benedictus de Spinoza

Proof.—We have shown that the idea of a modification of the human body involves the nature of an external body, in so far as that external body conditions the human body in a given manner. But, in so far as the external body is an individual, which has no reference to the human body, the knowledge or idea thereof is in God (II. ix.), in so far as God is regarded as affected by the idea of a further thing, which (II. vii.) is naturally prior to the said external body. Wherefore an adequate knowledge of the external body is not in God, in so far as he has the idea of the modification of the human body; in other words, the idea of the modification of the human body does not involve an adequate knowledge of the external body. Q.E.D.

PROP. XXVI. The human mind does not perceive any external body as actually existing, except through the ideas of the modifications of its own body.

Proof.—If the human body is in no way affected by a given external body, then (II. vii.) neither is the idea of the human body, in other words, the human mind, affected in any way by the idea of the existence of the said external body, nor does it in any manner perceive its existence. But, in so far as the human body is affected in any way by a given external body, thus far (II. xvi. and Coroll.) it perceives that external body. Q.E.D.

Corollary.—In so far as the human mind imagines an external body, it has not an adequate knowledge thereof.

Proof.—When the human mind regards external bodies through the ideas of the modifications of its own body, we say that it imagines (see II. xvii. note); now the mind can only imagine external bodies as actually existing. Therefore (by II. xxv.), in so far as the mind imagines external bodies, it has not an adequate knowledge of them. Q.E.D.

PROP. XXVII. The idea of each modification of the human body does not involve an adequate knowledge of the human body itself.

Proof.—Every idea of a modification of the human body involves the nature of the human body, in so far as the human body is regarded as affected in a given manner (II. xvi.). But, inasmuch as the human body is an individual which may be affected in many other ways, the idea of the said modification, &c. Q.E.D.

PROP. XXVIII. The ideas of the modifications of the human body, in so far as they have reference only to the human mind, are not clear and distinct, but confused.

Proof.—The ideas of the modifications of the human body involve the nature both of the human body and of external bodies (II. xvi.); they must involve the nature not only of the human body but also of its parts; for the modifications are modes (Post. iii.), whereby the parts of the human body, and, consequently, the human body as a whole are affected. But (by II. xxiv., xxv.) the adequate knowledge of external bodies, as also of the parts composing the human body, is not in God, in so far as he is regarded as affected by the human mind, but in so far as he is regarded as affected by other ideas. These ideas of modifications, in so far as they are referred to the human mind alone, are as consequences without premisses, in other words, confused ideas. Q.E.D.

Note.—The idea which constitutes the nature of the human mind is, in the same manner, proved not to be, when considered in itself alone, clear and distinct; as also is the case with the idea of the human mind, and the ideas of the ideas of the modifications of the human body, in so far as they are referred to the mind only, as everyone may easily see.