The Picture of Different Arts of the monk Theophilus seems to he the work of an author who lived at the end of the eleventh century and beginning of the twelfth. It is more exact and detailed than the work of Eraclius, and is composed of two parts—the first devoted to painting, and the second concerning the making of objects required in worship and the construction of buildings devoted to it. It describes in detail the furnace for melting glass and the manufacture of glass, the making of painted glass and colored earthen vessels, the working of iron, the melting of gold and silver and the working of them, enamel, the fabrication of vessels used in worship—the chalice, monstrance, etc.—organs, bells, cymbals, etc. The facts are curious, for they show that the industry of glass and metals had finally concentrated around the religious edifices. But the chemical technique is the same as that of the other books, though savoring of more modern influences; it brings us directly to the thirteenth and fourteenth centuries, from which period monuments and writings multiply more rapidly down into modern times. The derivation of technical traditions from antiquity becomes less and less manifest as intermediaries multiply and the arts tend to assume an original character.
The facts I have presented deserve our attention as a whole, in view of the course and renascence of scientific traditions. Sciences begin in fact with practice. The first object is to satisfy the necessities of life and the artistic wants that awaken early in civilizable races. But this same practice at once calls out more general ideas, which appeared first among mankind in a mystic form. With the Egyptians and Babylonians the same persons were at once the priests and the men of science. Thus the chemical industries were first exercised around the temples. The Book of the Sanctuary, the Book of Hermes, and the Book of Kemi, all synonymous denominations with the Greco-Egyptian alchemists, represent the earliest manuals of those industries. It was the Greeks, as in all other scientific branches, who gave these treatises a revision freed from the old hieratic forms, and who tried to draw from them a rational theory, capable in its turn, by a similar application, of pushing the practice forward and of serving as a guide to it. But the chemical science of the Greco-Egyptians never rid itself of the errors relative to transmission—which were sustained by the theory of primal matter—or of the religious and magic formulas formerly associated in the East with every industrial operation. Yet when scientific study proper perished with Roman civilization in the West, the wants of life kept up the imperishable practice of the shops with the progress required in the time of the Greeks, and the chemical arts subsisted; while the theories, too subtile or too strong for the minds