Much as he cared for expression,--"expression carried to its highest intensity of degree," as Walter Pater put it,--he never found it necessary to secure this expression at the cost of beauty. That he studied nature at first hand his works are clear evidence, but that did not preclude the choice of attractive subjects. His style is "so sober and contained," writes a recent critic, "so delicate and yet so healthy, so lovely and yet so free from prettiness, so full of sentiment, and devoid of sentimentality, that it is hard to find words for any critical characterization."[2] "Simplicity and nobility," the words of Cavalucci and Molinier, is perhaps the best phrase in which to sum up the art of Luca della Robbia. In his nephew, Andrea della Robbia, the founder of the school had a successor whose best work is worthy of the master's teaching. If he lacked the simplicity and severity of the older man, he surpassed him in depth of Christian sentiment. Sometimes, it is true, his tenderness verges on weakness, his devoutness on pietism. If we are tempted to charge him with monotony we must remember what pressure was brought upon a man whose works attained such immense popularity. The bambini of the Foundling Hospital and the Meeting of St. Francis and St. Dominick show the high level to which his art could rise. Antonio Rossellino and Mino da Fiesole may be classed together as sculptors to whom decorative effect was of first importance; they loved line and form for their intrinsic beauty. They delighted in elaborate and well ordered compositions. Elegance of design, delicacy and refinement in handling, are invariable qualities of their work. Such qualities were especially to be desired in the making of those sepulchral monuments which were so numerous in their period. Of the many fine works of this class in Tuscany each of these two sculptors contributed at least one of the best examples. It is superfluous to point out that the sweetness of these sculptors is perilously near the insipid, their grace too often formal. We are brought to realize the true greatness of the men when we behold the grave and tranquil beauty of the effigy of the Cardinal of Portugal, or the vigorous characterization of the bust of Bishop Salutati. It is John Addington Symonds who says the final word when he declares that the charm of the works of such men as Mino and Rossellino "can scarcely be defined except by similes." And these are the images which this master of similes calls up to our mind as we contemplate their works: "The innocence of childhood, the melody of a lute or a song bird as distinguished from the music of an orchestra, the rathe tints of early dawn, cheerful light on shallow streams, the serenity of a simple and untainted nature that has never known the world." [Footnote 1: Sidney Colvin.] [Footnote 2: Notes on _Vasari's Lives_, edited by E. H. and E. W. Blashfield and A. A. Hopkins.] II. ON BOOKS OF REFERENCE.