Again the seven metals were associated with the seven planets of the ancients—gold with the sun, silver with the moon, copper with Venus, lead with Saturn, iron with Mars, mercury with Mercury, tin with Jupiter, and these planets were supposed to exert influences upon the generation and development or perfection of the metals in the earth. The base metals were often supposed to be undergoing a gradual development toward perfection. This development toward perfection, that is, toward silver and gold, might be influenced by many factors, such as the relative quantities of their sulphurs or their mercuries, the relative purity or degree of perfection of these mercuries or sulphurs, the time and local conditions of their position in the earth and the influences of their planets. It was not considered improbable that chemists might by experiment devise means to hasten this natural growth.
These notions I believe fairly summarize the quite generally entertained theories which make up the representative chemical theory at the beginning of the sixteenth century. But this beginning of the sixteenth century is the period of the full flower of the Renaissance. The first impulse to this period of remarkable activity in all domains of human thought originated in Italy, and at least as early as the thirteenth century. It began with a renewed interest in ancient Greek and Roman literature and art, naturally also a fresh interest in philosophy. It was fostered by the Florentine Academy under the protection of the Medici, though its influence soon spread to other parts of Europe. A new spirit of criticism was awakened, and even the church was invaded by a long-forgotten stimulus to freedom of thought and discussion. As the movement spread, the aroused interest of men in all domains of human activity gave rise to many great movements. In the thirteenth century were founded the universities of Padua, Bologna, Salerno, Salamanca, Paris, Montpelier, Oxford and Cambridge. Some of these trace their foundation to clerical schools of even earlier date—but grew to importance and influence under the new impulse.
In the fourteenth century the German universities of Vienna, Prague and Heidelberg were founded, and the fifteenth century was marked by a rapid increase in the number of German and French universities and in their influence. An influence of similar importance to that of the universities of the time—and perhaps even surpassing that influence—arose from the invention of printing from movable metal types which occurred about the middle of the fifteenth century. The revival of interest in ancient literature as well as the promulgation of new ideas was vastly stimulated by the possibility of making written works accessible to a vastly increased constituency, and the interchange of information and ideas thus made possible contributed enormously to the great intellectual development which we call the renaissance. The