§ 17. Of Pietra Forte.[[102]]
The pietra forte is quarried in many places; it resists rain, sun, frost, and every trial, and demands time to work it, but it behaves very well; it does not exist in very large blocks.[[103]] Both by the Goths[[104]] and by the moderns have been constructed of this stone the most beautiful buildings to be found in Tuscany, as can be seen in Florence in the filling of the two arches, which form the principal doors of the oratory of Orsanmichele,[[105]] for these are truly admirable things and worked with the utmost care. Of this same stone there are throughout the city, as has been said, many statues and coats of arms,[[106]] as for instance in the Fortress and various other places. It is yellowish in colour with fine white veins that add greatly to its attractiveness, and it is sometimes employed for statues where there are to be fountains, because it is not injured by water. The walls of the palace of the Signori, the Loggia, and Orsanmichele are built of it, also the whole interior of the fabric of Santa Maria del Fiore, as well as all the bridges of our city, the Palace of the Pitti and that of the Strozzi families. It has to be worked with picks because it is very compact. Similarly, the other stones mentioned above must be treated in the manner already explained for the working of marble and other sorts of stones.
§ 18. Conclusion of Chapter.
After all however, good stones and well tempered tools apart, the one thing essential is the art, the intelligence, and the judgement of those who use them, for there is the greatest difference between artists, although they may all use the same method, as to the measure of grace and beauty they impart to the works which they execute. This enables us to discern and to recognize the perfection of the work done by those who really understand, as opposed to that of others who know less. As, therefore, all the excellence and beauty of the things most highly praised consist in that supreme perfection given to them by those who understand and can judge, it is necessary to strive with all diligence always to make things beautiful and perfect—nay rather, most beautiful and most perfect.
CHAPTER II.
The Description of squared Ashlar-work (lavoro di quadro) and of carved Ashlar-work (lavoro di quadro intagliato).
§ 19. The work of the Mason.
Having thus considered all the varieties of stone, which our artificers use either for ornament or for sculpture, let us now go on to say, that when stone is used for actual building, all that is worked with square and compasses and that has corners is called squared ashlar work (lavoro di quadro). The term (quadro) is given, because of the squared faces and corners, for every order of moulding or anything which is straight, projecting, or rectangular is work which takes the name of ‘squared,’ and so is it commonly known among the artificers. But when the stone does not remain plain dressed, but is chiselled into mouldings, friezes, foliage, eggs, spindles, dentels and other sorts of carving, the work on the members chosen to be so treated is called by the mason carved ashlar work (opera di quadro intagliato or lavoro di intaglio). Of this sort of plain and carved ashlar are constructed all the different Orders, Rustic, Doric, Ionic, Corinthian, and Composite, and so too, in the times of the Goths, the German work[[107]] (lavoro tedesco): and no kind of ornament can be made that is not founded on both sorts of the work above described. It is the same with breccias and marbles and every sort of stone, and also with bricks, used as a foundation for moulded stucco work. The same applies to walnut, poplar, and every kind of wood. But, because many do not recognize the difference between one Order and another, let us discuss distinctly and as briefly as possible in the chapter which follows, every mode and manner of these.
CHAPTER III.
Concerning the five Orders of Architecture, Rustic, Doric, Ionic, Corinthian, Composite, and also German Work.