After a theoretical introduction concerning the goal of architecture, its structural means, and the general principles to be derived therefrom, Durand deals as a convinced ‘constructor’ with various materials and their proper employment before treating of specific forms and their combination. Only in the second part of his work, concerned with ways of combining architectural elements, do the visual results of his theories become fully evident. There he presents in plan and in elevation various structural systems from trabeated colonnades of Greek and Roman inspiration to arcuated and vaulted forms of Renaissance or even round-arched medieval character. Among his specific examples, ‘vertical combinations’ of fifteenth- or sixteenth-century elements outnumber the strictly Classical paradigms (Figure 2); whole plates, moreover, are given to schemes that are not only generically Italianate, but of Early Christian, Romanesque, or even Gothic, rather than Renaissance, inspiration. Common to most of his examples is the insistent repetition of elements, both horizontally and vertically, and most characteristic is his interest in the varied skylines that central and corner towers can provide, as also in the incorporation of voids in architectural compositions in the form of loggias and pergolas. More monumental façades fronted by temple porticoes are in a minority, although colonnades are frequent enough in his presentation of such specific features as porches, vestibules, halls, galleries, and central spaces. Here are to be found most of the detailed formulas—almost all derived from Boullée and from the Grand Prix projects of the previous decade—which the next generation of architects would follow again and again throughout most of the western world. [Illustration: Figure 2. J.-N.-L. Durand: ‘Vertical Combinations’ (from _Précis des leçons_, 1805) ] In his second volume Durand turns from a consideration of architecture in terms of structural elements to a notably systematic presentation of buildings in terms of their varying functions. First he deals with urbanistic features, including not only bridges, streets, and squares, but also such supposedly essential elements of the ideal classicizing city as triumphal arches and tombs. A second section considers temples (not churches, it is amusing to note), palaces, treasuries, law courts, town halls, colleges, libraries, museums, observatories, lighthouses, markets, exchanges, custom houses, exhibition buildings, theatres, baths, hospitals, prisons, and barracks. Here were all the individual structures of the model Napoleonic city, of which Napoleon had time to build so few but of which the next decades in France and abroad were to see so many executed by Durand’s pupils and other emulators of his ideals.