Plato was the first man who perceived that this idea could be made to provide the philosopher with a vehicle of expression more powerful than any other. If a man will once plant himself firmly on the proposition that _he is_ the universe, that every emotion or expression of his mind is correlated in some way to phenomena in the external world, and that he shall say how correlated, he is in a position where the power of speech is at a maximum. His figures of speech, his tropes, his witticisms, take rank with the law of gravity and the precession of the equinoxes. Philosophical exaltation of the individual cannot go beyond this point. It is the climax.
This is the school of thought to which Emerson belonged. The sun and moon, the planets, are mere symbols. They signify whatever the poet chooses. The planets for the most part stay in conjunction just long enough to flash his thought through their symbolism, and no permanent relation is established between the soul and the zodiac. There is, however, one link of correlation between the external and internal worlds which Emerson considered established, and in which he believed almost literally, namely, the moral law. This idea he drew from Kant through Coleridge and Wordsworth, and it is so familiar to us all that it hardly needs stating. The fancy that the good, the true, the beautiful,--all things of which we instinctively approve,--are somehow connected together and are really one thing; that our appreciation of them is in its essence the recognition of a law; that this law, in fact all law and the very idea of law, is a mere subjective experience; and that hence any external sequence which we coördinate and name, like the law of gravity, is really intimately connected with our moral nature,--this fancy has probably some basis of truth. Emerson adopted it as a corner-stone of his thought.
Such are the ideas at the basis of Emerson's philosophy, and it is fair to speak of them in this place because they antedate everything else which we know of him. They had been for years in his mind before he spoke at all. It was in the armor of this invulnerable idealism and with weapons like shafts of light that he came forth to fight.