ii8 THE POPULAR SCIENCE MONTHLY. 



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 de- 

 tailed than the work of Eraclius, and is composed of two parts 

 the first devoted to painting, and the second concerning the mak- 

 ing of objects required in worship and the construction of build- 

 ings 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 inter- 

 mediaries multiply and the arts tend to assume an original char- 

 acter. 



The facts I have presented deserve our attention as a whole, in 

 view of the course and renascence of scientific traditions. Sci- 

 ences 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 chem- 

 ical 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 trea- 

 tises 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 serv- 

 ing 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 sub- 

 sisted ; while the theories, too subtile or too strong for the minds 



