Christoff Rudolff wrote Coss (1525), the first book of algebra to appear in German. This was significant in that German was the vernacular in much of northern and central Europe, and few among the rising bourgeois class could read Latin. As for the title, it referred to the word cosa or "thing," which was used to refer to anything unknown or indeterminate; since algebra dealt with such perplexities, it was known as the cossic art.
Rudolff was born, probably in 1499, in the village of Jauer in Silesia, which is now Jawor, Poland. In fact the area had been culturally Polish for centuries prior to his birth, but it had been dominated by Bohemians for some time, and would fall into Austrian hands in 1526. By that time Rudolff, who was probably brought up speaking German, had long since graduated from the University of Vienna.
Following his education at the university (1517-21), where he studied algebra, Rudolff continued living in the Austrian capital, where at the age of 26 he produced Coss. The book consisted of two parts, the first covering a number of topics—such as square and cube roots—necessary to the study of algebra in the second half. The latter was in turn divided into three sections, respectively covering first- and second-degree equations, rules for solving equations, and a series of algebraic problems.
No doubt in part because of its author's youth and his shocking use of German rather than Latin, the book attracted the opprobrium of other mathematicians, who claimed that Rudolff had lifted many of his problems and examples from existing works in the university library. On the other hand, German mathematician Michael Stifel (1487-1567) defended Rudolff's work, and even wrote a preface to a second edition.
Rudolff published Künstliche Rechnung mit der Ziffer und mit der Zahlpfennigen (1526), which addressed questions of computing and offered problems applicable to the rising commercial and industrial culture of Renaissance Europe. He followed this in 1530 with Exempelbüchlin, which contained nearly 300 more problems. Rudolff died in Vienna in 1545.