Key Arguments

• Every idea of a bodily modification involves the body’s nature only as affected in a given way (II. xvi.).
• Because the human body is an individual that may be affected in many other ways, the idea of one modification does not encompass its full nature, and thus is inadequate with respect to the body itself.

Source Quotes

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.).

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.

Key Concepts

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

Context

Ethics II, Prop. XXVII with Proof (abridged ending in text) (lines 1201–1334).