It is impossible to deny the power of suggestion wielded by those four lines, a power utterly disproportionate to what is actually said. The kinetic base of that stanza is only the proposition to a supposed tiger of a difficult problem in metaphysics. But above, below, and on either side of that question, completely enveloping it, is the phosphorescence of another speech, that we cannot so easily overhear. And who shall speak in fit terms of its potentiality? That glowing image, that surprised address; not in the enumeration of such things shall we come upon its secret. The test of a formula is, that it shall fit. It must enable us to co-ordinate scattered knowledge, and throw into a clear perspective the jumble of loose statements and scraps of information whose value we cannot but recognise, although they have remained outside previous schemes and done little more than disturb the equilibrium of once-established theories. It is a comfort and a joy to a thinker when he can say that a formula of his has almost been proposed by minds that have approached his problem along roads other than his own. When he can find statements, true in themselves but inadequate, pegging out, as it were, the ground from which his formula has been dug, he can feel that it is no mere chance that has given it a momentary appearance of usefulness. He can speak of it with the solid confidence that it has behind it the collaboration of his predecessors. We can bring such confidence to the use of this formula of kinetic and potential speech, for to whatever problem of literary theory or phenomenon of the history of literature we apply it, we find that it has been almost stated by those who have separately considered that problem or phenomenon. It smelts the ore that they have dug, and forges a weapon for the attack not of one problem, but of all. For example; though kinetic speech may be translated without loss from one language to another, potential speech would not be potential but kinetic if we were able to express it otherwise than by itself. This is what Shelley means when he denies the possibility of the translation of poetry, though he does not perceive the full reason, but only that the poetic quality of a poem is partly dependent on a succession of inimitable sounds. His statement, incomplete though it is, is a recognition of the duality of poetic speech. He does not for a moment contend that we cannot render the meaning; he sees that the meaning is not all. The body is one thing and the soul is another. If we leave the soul behind we have nothing but dead matter, fit for manure or food. Life, or poetry, delicate-footed, mysterious, gracious with knowledge of her mystery, is passed away and we cannot recapture her.