XX. I have, however, given enough instances of vitality shown in mere daring, whether wise, as surely in this last instance, or inexpedient; but, as a single example of the Vitality of Assimilation, the faculty which turns to its purposes all material that is submitted to it, I would refer the reader to the extraordinary columns of the arcade on the south side of the Cathedral of Ferrara. A single arch of it is given in Plate XIII. on the right. Four such columns forming a group, there are interposed two pairs of columns, as seen on the left of the same plate; and then come another four arches. It is a long arcade of, I suppose, not less than forty arches, perhaps of many more; and in the grace and simplicity of its stilted Byzantine curves I hardly know its equal. Its like, in fancy of column, I certainly do not know; there being hardly two correspondent, and the architect having been ready, as it seems, to adopt ideas and resemblances from any sources whatsoever. The vegetation growing up the two columns is fine, though bizarre; the distorted pillars beside it suggest images of less agreeable character; the serpentine arrangements founded on the usual Byzantine double knot are generally graceful; but I was puzzled to account for the excessively ugly type of the pillar, fig. 3, one of a group of four. It so happened, fortunately for me, that there had been a fair in Ferrara; and, when I had finished my sketch of the pillar, I had to get out of the way of some merchants of miscellaneous wares, who were removing their stall. It had been shaded by an awning supported by poles, which, in order that the covering might be raised or lowered according to the height of the sun, were composed of two separate pieces, fitted to each other by a _rack_, in which I beheld the prototype of my ugly pillar. It will not be thought, after what I have above said of the inexpedience of imitating anything but natural form, that I advance this architect's practice as altogether exemplary; yet the humility is instructive, which condescended to such sources for motives of thought, the boldness, which could depart so far from all established types of form, and the life and feeling, which out of an assemblage of such quaint and uncouth materials, could produce an harmonious piece of ecclesiastical architecture. XXI. I have dwelt, however, perhaps, too long upon that form of vitality which is known almost as much by its errors as by its atonements for them. We must briefly note the operation of it, which is always right, and always necessary, upon those lesser details, where it can neither be superseded by precedents, nor repressed by proprieties.