But the life-blood of an architectural design is proportion. Unfortunately one never notices its presence. Only when a building is out of proportion does one recognise that such a thing as proportion exists. And as it is the most subtle, so it is the most important factor in design—design small or large—Salisbury cathedral, the Pandolphini Palace, a Chippendale chair, or a Wedgewood vase. Alter the shape of the vase, and see the difference. In the same way, see if you can lengthen or shorten Salisbury nave for the better, or the transepts, or the porch, or the Lady chapel; or if you could heighten the Lady chapel or retro-choir to advantage; or if you could make the roofs an inch more acute or more flat. The proportions of this, as of every really great building, are subtle in the extreme; they interlock in all directions. Each part—_e.g._, the Lady chapel—is in proportion to the cathedral taken as a whole; each part is in proportion to contiguous parts; and each individual bit of each part is in proportion to the rest of it: _e.g._, in the Lady chapel the length, breadth and height of the walls, the slope of the roof, the dimensions of the windows, etc., are all in proportion to the Lady chapel taken as a whole. More than that—the proportions of the nave, choir, transepts, etc., are those which are suitable to a church 473 feet long and 404 feet high. If you built a church with a nave, choir and transepts exactly twice as large as those of Salisbury, it would not be in proportion, but out of proportion. The same lack of proportion would ensue if you copied the design of Salisbury in a parish church of exactly half its dimensions. Salisbury cathedral, like the Parthenon, cannot be copied with impunity, unless you preserve every dimension unaltered. Modern designers, not recognising this, have too often wrought themselves disappointment by unintelligent imitations of ancient work. [Illustration: CHAPTER HOUSE.] To the north and south another charming effect is seen in the gradual growth of the ornament upward. This, again, is to the credit of Time, and not of Elias de Dereham. From 1220 to 1330 window-tracery was ever growing richer day by day, and Salisbury cathedral was ever growing upward. And so the ornament culminates most rightly, yet most accidentally, in the higher stories of the transepts, in the tower and spire.