3. There is no difficulty in seeing that Plato’s divisions of knowledge

are based, first, on the fundamental antithesis of sensible and intellectual which pervades the whole pre-Socratic philosophy; in which is implied also the opposition of the permanent and transient, of the universal and particular. But the age of philosophy in which he lived seemed to require a further distinction;—numbers and figures were beginning to separate from ideas. The world could no longer regard justice as a cube, and was learning to see, though imperfectly, that the abstractions of sense were distinct from the abstractions of mind. Between the Eleatic being or essence and the shadows of phenomena, the Pythagorean principle of number found a place, and was, as Aristotle remarks, a conducting medium from one to the other. Hence Plato is led to introduce a third term which had not hitherto entered into the scheme of his philosophy. He had observed the use of mathematics in education; they were the best preparation for higher studies. The subjective relation between them further suggested an objective one; although the passage from one to the other is really imaginary (Metaph.). For metaphysical and moral philosophy has no connexion with mathematics; number and figure are the abstractions of time and space, not the expressions of purely intellectual conceptions. When divested of metaphor, a straight line or a square has no more to do with right and justice than a crooked line with vice. The figurative association was mistaken for a real one; and thus the three latter divisions of the Platonic proportion were constructed. There is more difficulty in comprehending how he arrived at the first term of the series, which is nowhere else mentioned, and has no reference to any other part of his system. Nor indeed does the relation of shadows to objects correspond to the relation of numbers to ideas. Probably Plato has been led by the love of analogy (Timaeus) to make four terms instead of three, although the objects perceived in both divisions of the lower sphere are equally objects of sense. He is also preparing the way, as his manner is, for the shadows of images at the beginning of the seventh book, and the imitation of an imitation in the tenth. The line may be regarded as reaching from unity to infinity, and is divided into two unequal parts, and subdivided into two more; each lower sphere is the multiplication of the preceding. Of the four faculties, faith in the lower division has an intermediate position (cp. for the use of the word faith or belief, (Greek), Timaeus), contrasting equally with the vagueness of the perception of shadows (Greek) and the higher certainty of understanding (Greek) and reason (Greek). The difference between understanding and mind or reason (Greek) is analogous to the difference between acquiring knowledge in the parts and the contemplation of the whole. True knowledge is a whole, and is at rest; consistency and universality are the tests of truth. To this self-evidencing knowledge of the whole the faculty of mind is supposed to correspond. But there is a knowledge of the understanding which is incomplete and in motion always, because unable to rest in the subordinate ideas. Those ideas are called both images and hypotheses—images because they are clothed in sense, hypotheses because they are assumptions only, until they are brought into connexion with the idea of good. The general meaning of the passage, ‘Noble, then, is the bond which links together sight...And of this kind I spoke as the intelligible...’ so far as the thought contained in it admits of being translated into the terms of modern philosophy, may be described or explained as follows:—There is a truth, one and self-existent, to which by the help of a ladder let down from above, the human intelligence may ascend. This unity is like the sun in the heavens, the light by which all things are seen, the being by which they are created and sustained. It is the IDEA of good. And the steps of the ladder leading up to this highest or universal existence are the mathematical sciences, which also contain in themselves an element of the universal. These, too, we see in a new manner when we connect them with the idea of good. They then cease to be hypotheses or pictures, and become essential parts of a higher truth which is at once their first principle and their final cause. We cannot give any more precise meaning to this remarkable passage, but we may trace in it several rudiments or vestiges of thought which are common to us and to Plato: such as (1) the unity and correlation of the sciences, or rather of science, for in Plato’s time they were not yet parted off or distinguished; (2) the existence of a Divine Power, or life or idea or cause or reason, not yet conceived or no longer conceived as in the Timaeus and elsewhere under the form of a person; (3) the recognition of the hypothetical and conditional character of the mathematical sciences, and in a measure of every science when isolated from the rest; (4) the conviction of a truth which is invisible, and of a law, though hardly a law of nature, which permeates the intellectual rather than the visible world. The method of Socrates is hesitating and tentative, awaiting the fuller explanation of the idea of good, and of the nature of dialectic in the seventh book. The imperfect intelligence of Glaucon, and the reluctance of Socrates to make a beginning, mark the difficulty of the subject. The allusion to Theages’ bridle, and to the internal oracle, or demonic sign, of Socrates, which here, as always in Plato, is only prohibitory; the remark that the salvation of any remnant of good in the present evil state of the world is due to God only; the reference to a future state of existence, which is unknown to Glaucon in the tenth book, and in which the discussions of Socrates and his disciples would be resumed; the surprise in the answers; the fanciful irony of Socrates, where he pretends that he can only describe the strange position of the philosopher in a figure of speech; the original observation that the Sophists, after all, are only the representatives and not the leaders of public opinion; the picture of the philosopher standing aside in the shower of sleet under a wall; the figure of ‘the great beast’ followed by the expression of good-will towards the common people who would not have rejected the philosopher if they had known him; the ‘right noble thought’ that the highest truths demand the greatest exactness; the hesitation of Socrates in returning once more to his well-worn theme of the idea of good; the ludicrous earnestness of Glaucon; the comparison of philosophy to a deserted maiden who marries beneath her—are some of the most interesting characteristics of the sixth book. Yet a few more words may be added, on the old theme, which was so oft discussed in the Socratic circle, of which we, like Glaucon and Adeimantus, would fain, if possible, have a clearer notion. Like them, we are dissatisfied when we are told that the idea of good can only be revealed to a student of the mathematical sciences, and we are inclined to think that neither we nor they could have been led along that path to any satisfactory goal. For we have learned that differences of quantity cannot pass into differences of quality, and that the mathematical sciences can never rise above themselves into the sphere of our higher thoughts, although they may sometimes furnish symbols and expressions of them, and may train the mind in habits of abstraction and self-concentration. The illusion which was natural to an ancient philosopher has ceased to be an illusion to us. But if the process by which we are supposed to arrive at the idea of good be really imaginary, may not the idea itself be also a mere abstraction? We remark, first, that in all ages, and especially in primitive philosophy, words such as being, essence, unity, good, have exerted an extraordinary influence over the minds of men. The meagreness or negativeness of their content has been in an inverse ratio to their power. They have become the forms under which all things were comprehended. There was a need or instinct in the human soul which they satisfied; they were not ideas, but gods, and to this new mythology the men of a later generation began to attach the powers and associations of the elder deities. The idea of good is one of those sacred words or forms of thought, which were beginning to take the place of the old mythology. It meant unity, in which all time and all existence were gathered up. It was the truth of all things, and also the light in which they shone forth, and became evident to intelligences human and divine. It was the cause of all things, the power by which they were brought into being. It was the universal reason divested of a human personality. It was the life as well as the light of the world, all knowledge and all power were comprehended in it. The way to it was through the mathematical sciences, and these too were dependent on it. To ask whether God was the maker of it, or made by it, would be like asking whether God could be conceived apart from goodness, or goodness apart from God. The God of the Timaeus is not really at variance with the idea of good; they are aspects of the same, differing only as the personal from the impersonal, or the masculine from the neuter, the one being the expression or language of mythology, the other of philosophy. This, or something like this, is the meaning of the idea of good as conceived by Plato. Ideas of number, order, harmony, development may also be said to enter into it. The paraphrase which has just been given of it goes beyond the actual words of Plato. We have perhaps arrived at the stage of philosophy which enables us to understand what he is aiming at, better than he did himself. We are beginning to realize what he saw darkly and at a distance. But if he could have been told that this, or some conception of the same kind, but higher than this, was the truth at which he was aiming, and the need which he sought to supply, he would gladly have recognized that more was contained in his own thoughts than he himself knew. As his words are few and his manner reticent and tentative, so must the style of his interpreter be. We should not approach his meaning more nearly by attempting to define it further. In translating him into the language of modern thought, we might insensibly lose the spirit of ancient philosophy. It is remarkable that although Plato speaks of the idea of good as the first principle of truth and being, it is nowhere mentioned in his writings except in this passage. Nor did it retain any hold upon the minds of his disciples in a later generation; it was probably unintelligible to them. Nor does the mention of it in Aristotle appear to have any reference to this or any other passage in his extant writings.