translucent, tenuous, half-spiritual substance of Shelley, but aggressively massive and opaque, tense with solidity. And he had in an eminent degree the quick and eager apprehension of space--relations which usually goes with these developed sensibilities of eye and muscle. There is a hint of it in an early anecdote. "Why, sir, you are quite a geographer!" he reported his mother to have said to him when, on his very first walk with her, he had given her an elaborate imaginary account of "his houses and estates."[62] But it was only late in life that this acute plasticity and concreteness of his sensibility found its natural outlet. When in their last winter at Rome (1860-61) he took to clay-modelling, it was with an exultant rapture which for the time thrust poetry into the shade. "The more tired he has been, and the more his back ached, poor fellow," writes his wife, "the more he has exulted and been happy--no, nothing ever made him so happy before."[63] This was the immense joy of one who has at length found the key after half a lifetime of trying at the lock. [Footnote 62: Mrs Orr, _Life_, p. 24.] [Footnote 63: Mrs Browning's _Letters_, March 1861.] III. And yet realism as commonly understood is a misleading term for Browning's art. If his keen objective senses penned his imagination, save for a few daring escapades, within the limits of a somewhat normal actuality, it exercised, within those limits, a superb individuality of choice. The acute observer was doubled with a poet whose vehement and fiery energy and intense self-consciousness influenced what he observed, and yet far more what he imagined and what he expressed. It is possible to distinguish four main lines along which this determining bias told. He gloried in the strong sensory-stimulus of glowing colour, of dazzling light; in the more complex _motory_-stimulus of intricate, abrupt, and plastic form,--feasts for the agile eye; in all the signs of power, exciting a kindred joy by sympathy; and in all the signs of conscious life or "soul," exciting a joy which only reaches its height when it is enforced by those more elemental and primitive springs of joy, when he is engaged with souls that glow like a flower or a gem, with souls picturesquely complex and diversified, or vehement, aspiring, heroic. In each of those four domains, light and colour, form, power, soul, Browning had a profound, and in the fullest sense creative, joy, which in endless varieties and combinations dominated his imagination, controlled and pointed its flight, and determined the contents, the manner, and the atmosphere of his poetic work. To trace these operations in detail will be the occupation of the five following sections. IV. 1. JOY IN LIGHT AND COLOUR.