This architecture, commonly called "Gothic," though in conception perfect, like the theory of a Christian character, never reached an actual perfection, having been retarded and corrupted by various adverse influences; but it reached its highest perfection, hitherto manifested, about the close of the thirteenth century, being then indicative of a peculiar energy in the Christian mind of Europe. In the course of the fifteenth century, owing to various causes which I have endeavored to trace in the preceding pages, the Christianity of Europe was undermined; and a Pagan architecture was introduced, in imitation of that of the Greeks and Romans. The architecture of the Greeks and Romans themselves was not good, but it was natural; and, as I said before, good in some respects, and for a particular time. But the imitative architecture introduced first in the fifteenth century, and practised ever since, was neither good nor natural. It was good in no respect, and for no time. All the architects who have built in that style have built what was worthless; and therefore the greater part of the architecture which has been built for the last three hundred years, and which we are now building, is worthless. We must give up this style totally, despise it and forget it, and build henceforward only in that perfect and Christian style hitherto called Gothic, which is everlastingly the best. This is the theorem of these volumes. In support of this theorem, the first volume contains, in its first chapter, a sketch of the actual history of Christian architecture, up to the period of the Reformation; and, in the subsequent chapters, an analysis of the entire system of the laws of architectural construction and decoration, deducing from those laws positive conclusions as to the best forms and manners of building for all time. The second volume contains, in its first five chapters, an account of one of the most important and least known forms of Christian architecture, as exhibited in Venice, together with an analysis of its nature in the fourth chapter; and, which is a peculiarly important part of this section, an account of the power of color over the human mind.