I shall proceed to give you some notion of the individual works of this author, taking them in the order in which he mentions them, which is that of their production. The _Memorie degli Architetti_ is preceded by a general view of the principles of the art. He contends that architecture is an imitative art, and he makes its claim to be considered as one of the fine arts, to consist in this imitation. In this he is evidently wrong, as the claim of this, or any other, to a place among the fine arts, depends on its power of exciting mental emotion. He then proceeds to give what he considers as fixed and unalterable rules, which, as they are here given in a condensed form, and are the same which he insists upon in his later works, I shall translate. “Architecture, like every other fine art, is subject to the following general rules. 1. “In all its productions, we should find an agreeable correspondence of the parts with the whole. This is known by the name of _symmetry_. 2. “It ought to have variety, lest the spectator’s attention should be wearied; and _unity_, which is opposed to confusion and disorder. This is comprehended in the term _eurithmia_. 3. “Convenience, or suitableness, is also a necessary quality. This consists in a just application of symmetry and eurithmia, and of that relation which ought to subsist between an edifice, and the purpose to which it is applied; between the details of ornament, and the general appearance of the building, chusing the most appropriate, and the style which accords best with the magnificence or simplicity of the structure. 4. “If architecture be the daughter of necessity, every beauty which it possesses ought to connect itself with that necessity, and to appear made for some useful purpose. In every art which administers to pleasure, the artifice ought not to be discovered; every thing done for mere ornament is a defect. 5. “The principal ornaments of architecture are its orders, which in fact are rather to be considered as the skeleton, and most essential part of the edifice, than as mere ornament. We might therefore define the orders, _necessary ornaments arising from the nature of the edifice_. All the other decorations of architecture are subject to the same law. 6. “Consequently, in architecture the decoration is the result of the construction. Nothing is ever to be seen in a fabric, that has not its appropriate use, and is not an essential part of the structure: the office that it indicates, it ought to perform. 7. “Consequently, nothing is admissible for which a good reason cannot be rendered.