From the position we are now placed in, surrounded by the accumulated talent of many centuries, it is easy to take a retrospective view of the progress of art; and it is only by so doing that we can arrive at a just estimate of the great artists who advanced it beyond the age in which they lived, and this seems mainly to have been achieved by a close observance of nature. As in philosophy the genius of Bacon, by investigating the phenomena of visible objects, put to flight and dissipated the learned dogmas of the school of Aristotle, so in sculpture the purity and simplicity of the forms of Phidias established a line of demarcation between his own works and those of the formal, symmetrical, and dry sculpture of his predecessors. Sculpture, till then, lay fettered and bound up in the severity of Egyptian Hieroglyphics. Likewise we perceive the genius of Michael Angelo and Raffaelle setting aside the stiffness and profile character existing in the works of Signorelli and Masaccio. In Venice, Titian emancipated the arts from the grasp of Giovanni Bellini. In Germany, Rubens must be considered the great translator of art out of a dead language into a living one, to use a metaphor, and into one that, like music, is universal. Previous to Rembrandt, the pupils of Rubens had thrown off every affinity not only to Gothic stiffness, but even to that degree of regularity of composition which all classes of historical subjects require. Independent of Rubens and his pupils, we find Rembrandt was aware of the great advances made in natural representations of objects by Adrian Brauwer, (several of whose works, by the catalogue given of his effects, were in his possession;) therefore, as far as transparency and richness, with a truthfulness of tint, are concerned, Brauwer had set an example. But in the works of Rembrandt we perceive a peculiarity entirely his own—that of enveloping parts in beautiful obscurity, and the light again emerging from the shadow, like the softness of moonlight partially seen through demi-transparent clouds, and leaving large masses of undefined objects in darkness. This principle he applied to compositions of even a complicated character, and their bustle and noise were swallowed up in the stillness of shadow. If breadth constitutes grandeur, Rembrandt's works are exemplifications of mysterious sublimity to the fullest extent. This "darkness visible," as Milton expresses it, belongs to the great founder of the school of Holland, and to him alone. Flinck, Dietricy, De Guelder, and others his pupils, give no idea of it; their works are warm, but they are without redeeming cool tints; they are yellow without pearly tones; and in place of leading the eye of the spectator into the depths of aërial perspective, the whole work appears on the surface of the panel. There are none of those shadows "hanging in mid air," which constitute so captivating a charm in the great magician of chiaro-scuro; not only are objects of solidity surrounded by softening obscurity, but the contiguous atmosphere gives indications of the influence of the light and shade. To these principles the art is indebted for breadth and fulness of effect, which constitute the distinct characteristics between the early state and its maturity—and to Rembrandt we owe the perfection of this fascinating quality.