Of the many broad divisions under which architecture may be considered, none appear to me more significant than that into buildings whose interest is in their walls, and those whose interest is in the lines dividing their walls. In the Greek temple the wall is as nothing; the entire interest is in the detached columns and the frieze they bear; in French Flamboyant, and in our detestable Perpendicular, the object is to get rid of the wall surface, and keep the eye altogether on tracery of line; in Romanesque work and Egyptian, the wall is a confessed and honored member, and the light is often allowed to fall on large areas of it, variously decorated. Now, both these principles are admitted by Nature, the one in her woods and thickets, the other in her plains, and cliffs, and waters; but the latter is pre-eminently the principle of power, and, in some sense, of beauty also. For, whatever infinity of fair form there may be in the maze of the forest, there is a fairer, as I think, in the surface of the quiet lake; and I hardly know that association of shaft or tracery, for which I would exchange the warm sleep of sunshine on some smooth, broad, human-like front of marble. Nevertheless, if breadth is to be beautiful, its substance must in some sort be beautiful; and we must not hastily condemn the exclusive resting of the northern architects in divided lines, until at least we have remembered the difference between a blank surface of Caen stone, and one mixed from Genoa and Carrara, of serpentine with snow: but as regards abstract power and awfulness, there is no question; without breadth of surface it is in vain to seek them, and it matters little, so that the surface be wide, bold and unbroken, whether it be of brick or of jasper; the light of heaven upon it, and the weight of earth in it, are all we need: for it is singular how forgetful the mind may become both of material and workmanship, if only it have space enough over which to range, and to remind it, however feebly, of the joy that it has in contemplating the flatness and sweep of great plains and broad seas. And it is a noble thing for men to do this with their cut stone or moulded clay, and to make the face of a wall look infinite, and its edge against the sky like an horizon: or even if less than this be reached, it is still delightful to mark the play of passing light on its broad surface, and to see by how many artifices and gradations of tinting and shadow, time and storm will set their wild signatures upon it; and how in the rising or declining of the day the unbroken twilight rests long and luridly on its high lineless forehead, and fades away untraceably down its tiers of confused and countless stone. IX. This, then, being, as I think, one of the peculiar elements of sublime architecture, it may be easily seen how necessarily consequent upon the love of it will be the choice of a form approaching to the square for the main outline.