This analogy, however, we may leave for the present. The one point which it is indispensable to insist on here is, that man can progress or tend towards success only by following the principles and copying, so far as he can understand them, the processes which Nature employs in her works; but he can never succeed in anything by copying forms without reference to principles. If we could find Nature making trees like stones, or animals like trees, or birds like fishes, or fishes like mammalia, or using any parts taken from one kingdom for purposes belonging to another, it would then be perfectly legitimate for us to use man’s stature as the modulus for a Doric, or woman’s as that of an Ionic column—to build cathedrals like groves, and make windows like leaves, or to estimate their beauty by their resemblance to such objects; but all such comparisons proceed on an entire mistake of what imitation of Nature really means. It is the merest and most absolute negation of reason to apply to one purpose things that were designed for another, or to imitate them when they have no appropriateness; but it is our highest privilege to understand the processes of Nature. To apply these to our own wants and purposes is the noblest use of human intellect and the perfection of human wisdom. So instinctively, but so literally, has this correct process of imitating Nature been followed in all true styles of architecture, that we can always reason regarding them as we do with reference to natural objects. Thus, if an architect finds in any quarter of the globe a Doric or Corinthian capital with a few traces of a foundation, he can, at a glance, tell the age of the temple or building to which it belonged. He knows who the people were who erected it, to what purpose it was dedicated, and proceeds at once to restore its porticos, and without much uncertainty can reproduce the whole fabric. Or if he finds a few Gothic bases in situ, with a few mouldings or frusta of columns, by the same process he traces the age, the size, and the purposes of the building before him. A Cuvier or an Owen can restore the form and predicate the habits of an extinct animal from a few fragments of bone, or even from a print of a foot. In the same manner an architect may, from a few fragments of a building, if of a true style of architecture, restore the whole of its pristine forms, and with almost the same amount of certainty. This arises wholly because the architects of former days had correct ideas of what was meant by imitation of Nature. They added nothing to their buildings which was not essential; there was no detail which had not its use, and no ornament which was not an elaboration or heightening of some essential part, and hence it is that a true building is as like to a work of Nature as any production of man’s hands can be to the creations of his Maker. XVI.—ASSOCIATION.