Kusursuz Dairenin Merkezi: Serlio ve Mimarinin İlk Biçimleri

Plane curvilinear two-angled surface will be of two curved lines, that is, circular, which figure will serve for many things in this book, and from which one will draw the exact norm, that is, the square, and from this figure is drawn the shape of those modern arches, which are called pointed thirds, which in many buildings are seen at doors, at arches, and at windows. From the perfect circle one will have the center, the circumference, and the diameter. Semicircle in which is found the plumb line falling upon the diameter, from which is born the right angle, and it makes the half diameter. Perfect square will be of four lines of equal length joined together, and they will make four right angles. Once the Architect is instructed in the knowledge of the past figures, it will be necessary to proceed further, that is, to know how to increase them, diminish them, and partition them proportionally, and to reduce an imperfect form to its perfection, and to that value that it was perfect, and of its first form.