Far back in the middle ages men turned their attention to the “ferment” and to fermentation. Much was written, much nonsense and humbug published; almost no results were attained, but the beginning was made. Men of the later time grasped the collected material, regulated and systematized the inquiry and vied with each other in its prosecution. Struggle and activity were then so universal that there was a disposition to consider fermentation a special branch of chemistry, and after treating of the fermentation of wine, beer, vinegar, etc., it was suggested that the whole vital process might be nothing more than a continual fermentation. [3] _Galliæ et Hispaniæ frumento in potum resoluto spuma ita concreta pro fermento utuntur; qua de causa levior illis quam ceteris panis est._ [4] _De fermento, sine quo ars alchemiæ perfeci et compleri non potest._ [Illustration: View of a Brewery connected with a convent in Bohemia (14th century), as described by Thaddeus Hagecius ab Hayek, 1585, in his book, written in Latin, under the title, _De cerevisia_.] Notwithstanding all that has been said it seems best to date the new epoch definitely from the beginning of the sixteenth century, and this although we can reckon no names or events of importance in the year 1501, and must pass over a number of decades to reach Libarius the first theorist of the second epoch. The reasons for such a division are various, partly to remove as far as possible all uncertainty from the discussion, partly because at that memorable time the general break with blind tradition and the development of new intellectual and social conditions took place in such a manner as to have a direct influence on the history of beer and so connect the general revolution with the province of zymotechnic inquiry. If we date from Libarius we commit an anachronism, for he stands in the full light of the new era. In short, beer and its history are so intimately related to social life and its development that we cannot consider the former alone and without regard to the latter. The oldest book in this sort of literature at present known, was published in 1530, under the title, “An Excellent Little Book of the Making of Wine and Beer so that they may be Useful and Wholesome to Man. Printed at Erfurt by Melchior Sachssen at Noah’s Ark.”[5] In 1551, a scholar (Plocotamus) wrote “_De natura cerevisiarum et de mulso_,” and somewhat later (1585) Thaddeus Hagecius ab Hayek wrote in Latin a work with the title “_De cerevisia ejusque conficiendi ratione, natura, viribus et facultatibus_.” More important than any of these is a book written in German by Heinrich Knaust, its value consisting not so much in historical deductions as in a review, grounded on the personal knowledge of the author, of the facts regarding beer in his time. It is chiefly through this volume that we are able to form a clear conception of the high development and actual power of beer at the end of the sixteenth century. On the first