I will quote the passage; it goes to the root of the matter; and whenever I read it, I seem to hear a well-known sculptor as he talked one night to me of the spiritual way in which marble, so soft and yet so firm, answered like living material to his tool, sending flame into it, and then seemed, as with a voice, to welcome the emotion which, flowing from him through the chisel, passed into the stone.
But of the stuffs one can be master of, How I divined their capabilities! From the soft-rinded smoothening facile chalk That yields your outline to the air's embrace, Half-softened by a halo's pearly gloom: Down to the crisp imperious steel, so sure To cut its one confided thought clean out Of all the world.

But marble!--'neath my tools More pliable than jelly--as it were Some clear primordial creature dug from depths In the earth's heart, where itself breeds itself.
And whence all baser substance may be worked; Refine it off to air, you may--condense it Down to the diamond;--is not metal there, When o'er the sudden speck my chisel trips?
-- Not flesh, as flake off flake I scale, approach, Lay bare those bluish veins of blood asleep?
Lurks flame in no strange windings where, surprised By the swift implement sent home at once, Flushes and glowings radiate and hover About its track?
But Jules finds that Phene, whom he has been deceived into believing an intelligence equal to his own, does not understand one word he has said, is nothing but an uneducated girl; and his dream of perfection in the marriage of Art and Love vanishes away, and with the deception the aims and hopes of his art as it has been.

And Browning makes this happen of set purpose, in order that, having lost satisfaction in his art-ideal, and then his satisfaction in that ideal realised in a woman--having failed in Art and Love--he may pass on into a higher aim, with a higher conception, both of art and love, and make a new world, in the woman and in the art.

He is about to accept the failure, to take only to revenge on his deceivers, when Pippa sings as she is passing, and the song touches him into finer issues of thought.

He sees that Phene's soul is, like a butterfly, half-loosed from its chrysalis, and ready for flight.
The sight and song awake a truer love, for as yet he has loved Phene only through his art.