In the Parmenides, on the contrary, everything is the reverse of this. Parmenides and Zeno exchange good-humoured smiles at Socrates’s criticism, when the bystanders expect them to grow angry. They listen to Socrates while he propounds Plato’s doctrine of Ideas; and reply to him with solid arguments which he does not answer, and which have never yet been answered. Parmenides, in a patronising way, lets him off; and having done this, being much entreated, he pronounces a discourse concerning the One and the Many; which, obscure as it may seem to us, was obviously intended to be irrefutable: and during the whole of this part of the Dialogue, the friend of Socrates appears only as a passive respondent, saying Yes or No as the assertions of Parmenides require him to do; just in the same way in which the opponents of Socrates are represented in other Dialogues.
These circumstances, to which other historical difficulties might be added, seem to show plainly that the Parmenides must be regarded as an Eleatic, not as a Platonic Dialogue;—as composed to confute, not to assert, the Platonic doctrine of Ideas.
The Platonic doctrine of Ideas has an important bearing upon the philosophy of Science, and was suggested in a great measure by the progress which the Greeks had really made in Geometry, Astronomy, and other Sciences, as I shall elsewhere endeavor to show. This doctrine has been recommended in our own time,[1] as containing “a mighty substance of imperishable truth.” It cannot fail to be interesting to see in what manner the doctrine is presented by those who thus judge of it. The following is the statement of its leading features which they give us.
[1] A. Butler’s Lectures, Second Series, Lect. viii. p. 132.
Man’s soul is made to contain not merely a consistent scheme of its own notions, but a direct apprehension of real and eternal laws beyond it. These real and eternal laws are things intelligible, and not things sensible. The laws, impressed upon creation by its Creator, and apprehended by man, are something equally distinct from the Creator [493] and from man; and the whole mass of them may be termed the World of Things purely Intelligible.
Further; there are qualities in the Supreme and Ultimate Cause of all, which are manifested in his creation; and not merely manifested, but in a manner—after being brought out of his super-essential nature into the stage of being which is below him, but next to him—are then, by the causative act of creation, deposited in things, differencing them one from the other, so that the things participate of them (μετέχουσι), communicate with them (κοινωνοῦσι).
The Intelligence of man, excited to reflection by the impressions of these objects, thus (though themselves transitory) participant of a divine quality, may rise to higher conceptions of the perfections thus faintly exhibited; and inasmuch as the perfections are unquestionably real existences, and known to be such in the very act of contemplation, this may be regarded as a distinct intellectual apprehension of them;—a union of the Reason with the Ideas in that sphere of being which is common to both.
Finally, the Reason, in proportion as it learns to contemplate the Perfect and Eternal, desires the enjoyment of such contemplations in a more consummate degree, and cannot be fully satisfied except in the actual fruition of the Perfect itself.
These propositions taken together constitute the Theory of Ideas. When we have to treat of the Philosophy of Science, it may be worth our while to resume the consideration of this subject.