That is what his poems are fundamentally—­the Skylark, and the Witch of the Atlas, and the Sensitive Plant no less than the grander pieces.  He infused into his gossamer world the strength of his heroic conscience.  He felt that what his imagination pictured was a true symbol of what human experience should and might pass into.  Otherwise he would have been aware of playing with idle images; his poetry would have been mere millinery and his politics mere business; he would have been a worldling in art and in morals.  The clear fire, the sustained breath, the fervent accent of his poetry are due to his faith in his philosophy.  As Mrs. Shelley expressed it, he “had no care for any of his poems that did not emanate from the depths of his mind, and develop some high and abstruse truth.”  Had his poetry not dealt with what was supreme in his own eyes, and dearest to his heart, it could never have been the exquisite and entrancing poetry that it is.  It would not have had an adequate subject-matter, as, in spite of Matthew Arnold, I think it had; for nothing can be empty that contains such a soul.  An angel cannot be ineffectual if the standard of efficiency is moral; he is what all other things bring about, when they are effectual.  And a void that is alive with the beating of luminous wings, and of a luminous heart, is quite sufficiently peopled.  Shelley’s mind was angelic not merely in its purity and fervour, but also in its moral authority, in its prophetic strain.  What was conscience in his generation was life in him.

The mind of man is not merely a sensorium.  His intelligence is not merely an instrument for adaptation.  There is a germ within, a nucleus of force and organisation, which can be unfolded, under favourable circumstances, into a perfection inwardly determined.  Man’s constitution is a fountain from which to draw an infinity of gushing music, not representing anything external, yet not unmeaning on that account, since it represents the capacities and passions latent in him from the beginning.  These potentialities, however, are no oracles of truth.  Being innate they are arbitrary; being a priori they are subjective; but they are good principles for fiction, for poetry, for morals, for religion.  They are principles for the true expression of man, but not for the true description of the universe.  When they are taken for the latter, fiction becomes deception, poetry illusion, morals fanaticism, and religion bad science.  The orgy of delusion into which we are then plunged comes from supposing the a priori to be capable of controlling the actual, and the innate to be a standard for the true.  That rich and definite endowment which might have made the distinction of the poet, then makes the narrowness of the philosopher.  So Shelley, with a sort of tyranny of which he does not suspect the possible cruelty, would impose his ideal of love and equality upon all creatures; he would make enthusiasts of clowns and doves of vultures.