The five styles above named--_i.e._ the Egyptian, the Greek, the Pointed Gothic, the Norman, and the Moresque--are so much distinguished from all other modes of building by the integrity with which a single idea is carried out in every detail, that in comparison with them there is no other manner which deserves to be called a style. And it is hard to conjecture the possibility of the development in the future of any sixth style which shall deserve to rank with them; for these five seem to have exhausted the five possible modes in which weight or mass of material--apparently the foundations of all architectural expression--can be treated. Two of these styles, the Norman and the Moresque, though equal to the others in artistic integrity, are immeasurably inferior to them in significance; the first three having dealt with and exhausted the only modes in which the primary fact of weight of material in stone construction can be subordinated to religious expression, and the field itself of religious expression in architecture having been in like manner cleared by these styles: for when the Material, the Rational, and the Spiritual have once found utterance in stone--as they have done in the temple-architectures of Egypt, Greece, and Northern Europe--what fourth religious aspect remains to inspire a new art? It is proposed in these papers to consider the several expressional themes of the five great architectures, and to give a brief exposition of the way in which they are worked out. It should be premised, however, that as it does not require a knowledge of how an effect is produced in order to feel that effect, so it is not pretended that any very distinct consciousness of the adaptation of means to expressional ends must have existed in the minds of the inventors of the great styles of architecture. All artistic production involves a large element of lucky accident, of which the true artist alone knows how to avail himself; and it is often from a lucky accident in a happy season that a great work or a great art will take its origin, as the dropping of a grain of sand into a saturated solution of certain salts will form the centre and cause of its sudden crystallisation. As sound philosophy is only sound sense spread out, so true criticism of great work is only right perception spread out; and the use of criticism of such work is not so much to teach men to enjoy it, as to enable them to pronounce a prompt and assured and demonstrable condemnation of bad or inferior work when false or exaggerated claims are put forth in its favour.