As in comparative anatomy it is easy, from a single bone, to designate and describe the animal to which it belonged, so in architecture it is easy to restore, by a few fragments, any ancient building. In consequence of the known simplicity and regularity of most antique edifices, the task of restoration, by means of drawings and models, is much less difficult than might be supposed. The ground work, or some sufficient parts of it, commonly extant, shows the length and breadth of the building, with the positions of the walls, doors and columns. A single column, or part of a column, whether standing or fallen, with a fragment of the entablature, furnishes data from which the remainder of the colonnade and the height of the edifice can be made out. A single stone from the cornice of the pediment, is sufficient to give the angle of inclination, and consequently the height of the roof. In this way the structure of many beautiful edifices has been accurately determined, when in so ruinous a state as scarcely to have left one stone upon another.