The marvel is, how Khufu came suddenly to have so magnificent a thought as that of constructing an edifice double the height of any previously existing, covering five times the area, and containing ten times the mass. Architecture does not generally proceed by "leaps and bounds;" but here was a case of a sudden extraordinary advance, such as we shall find it difficult to parallel elsewhere. An attempt has been made to solve the mystery by the supposition that all pyramids were gradual accretions, and that their size marks simply the length of a king's reign, each monarch making his sepulchral chamber, with a small pyramid above it, in his first year, and as his reign went on, adding each year an outer coating; so that the number of these coatings tells the length of his reign, as the age of a tree is known from the number of its annual rings. In this case there would have been nothing ideally great in the conception of Khufu--he would simply have happened to erect the biggest pyramid because he happened to have the longest reign; but, except in the case of the "Third Pyramid," there is a unity of design in the structures which implies that the architect had conceived the whole structure in his mind from the first. The lengths of the several parts are proportioned one to another. In the "Great Pyramid," the main chamber would not have needed the five relieving chambers above it unless it was known that it would have to be pressed down by a superincumbent mass, such as actually lies upon it. Moreover, how is it possible to conceive that in the later years of a decrepid monarch, the whole of an enormous pyramid could be coated over with huge blocks--and the blocks are largest at the external surface--the work requiring to be pushed each year with more vigour, as becoming each year greater and more difficult? Again, what shall we say of the external finish? Each pyramid was finally smoothed down to a uniform sloping surface. This alone must have been a work of years. Did a pyramid builder leave it to his successor to finish his pyramid? It is at least doubtful whether any pyramid at all would ever have been finished had he done so.