Aristotle described the earth as a cold and dry body and paid no attention to the phenomenon of terrestrial heat. Renaissance physicians, by contrast, when seeking to understand the origin of hot springs in the context of their balneological studies, came to defend a theory of subterranean fires. This tradition, which started in Italy, became widely known through the works of Georgius Agricola. But although it had implications for the explanation of further natural phenomena, it remained almost exclusively confined to medical circles. As far as physics as an academic discipline was concerned, the ideas concerning subterranean fire were hardly taken note of. Only with the collapse of Aristotelian philosophy in the seventeenth century could these by then "old innovations" obtain a wider significance.
Historians of science have studied book dedications mostly as an expression of patronage relationships, but this was not their only reason of existence. In the first part of the article, the general functions of book dedications are analyzed. As a starting-point, the article uses one specific, fairly homogenous genre, the academic disputation. Dedicatees fall into three broad categories: parents and relatives, regents and nobles, and professors. The corresponding functions can be defined as: maintaining an existing relationship, asking for specific favors, and enhancing the author’s credibility. The same functions can be recognized in other genres, although with many exceptions and deviations. In the second part of the article, two concrete examples are analyzed in detail, Rheticus’ Narratio prima and Galileo’s Sidereus Nuncius. As it appears, rather than follow a consistent strategy, their authors had to navigate between conflicting demands and considerations.