Correspondence, by Benedict de Spinoza, , at sacred-texts.com
[Spinoza answers by references to the first three books of the Ethics.]
Dear Sir,I am glad that you have at last had occasion to refresh me with one of your letters, always most welcome to me. I heartily beg that you will frequently repeat the favour, &c.
I proceed to consider your doubts: to the first I answer, that the human mind can only acquire knowledge of those things which the idea of a body actually existing involves, or of what can be inferred from such an idea. For the power of anything is defined solely by its essence (Ethics, III. vii.); the essence of the mind (Ethics, II. xiii.) consists solely in this, that it is the idea of body actually existing; therefore the mind's power of understanding only extends to things, which this idea of body contains in itself, or which follow therefrom. Now this idea of body does not involve or express any of God's attributes, save extension and thought. For its object (ideatum), namely, body (by Ethics, II. vi), has God for its cause, in so far as He is regarded under the attribute of extension, and not in so far as He is regarded under any other; therefore (Ethics, I. ax. vi.) this idea of the body involves the knowledge of God, only
in so far as He is regarded under the attribute of extension. Further, this idea, in so far as it is a mode of thinking, has also (by the same proposition) God for its cause, in so far as He is regarded as a thinking thing, and not in so far as He is regarded under any other attribute. Hence (by the same axiom) the idea of this idea involves the knowledge of God, in so far as He is regarded under the attribute of thought, and not in so far as He is regarded under any attribute. It is therefore plain, that the human mind, or the idea of the human body neither involves nor expresses any attributes of God save these two. Now from these two attributes, or their modifications, no other attribute of God can (Ethics, I. x.) be inferred or conceived. I therefore conclude, that the human mind cannot attain knowledge of any attribute of God besides these, which is the proposition you inquire about. With regard to your question, whether there must be as many worlds as there are attributes, I refer you to Ethics II. vii. note.
Moreover this proposition might be proved more readily by a reduction to the absurd; I am accustomed, when the proposition is negative, to employ this mode of demonstration as more in character. However, as the question you ask is positive, I make use of the positive method, and ask, whether one thing can be produced from another, from which it differs both in essence and existence; for things which differ to this extent seem to have nothing in common. But since all particular things, except those which are produced from things similar to themselves, differ from their causes both in essence and existence, I see here no reason for doubt.
The sense in which I mean that God is the efficient cause of things, no less of their essence than of their existence, I think has been sufficiently explained in Ethics I. xxv. note and corollary. The axiom in the note to Ethics I. x., as I hinted at the end of the said note, is based on the idea which we have of a Being absolutely infinite, not on the fact, that there are or may be beings possessing three, four, or more attributes.
Lastly, the examples you ask for of the first kind are, in thought, absolutely infinite understanding; in extension, motion and rest; an example of the second kind is the
sum of the whole extended universe (facies totius universi), which, though it varies in infinite modes, yet remains always the same. Cf. Ethics II. note to Lemma vii. before Prop. xiv.
Thus, most excellent Sir, I have answered, as I think, the objections of yourself and your friend. If you think any uncertainty remains, I hope you will not neglect to tell me, so that I may, if possible, remove it.
The Hague, 29 July, 1675.