173The subject of this chapter is the changing character of natural philoso-
phy and the attitudes of its cultivators toward it from the restabilization
of Europe around 1660 to the end of the eighteenth century. What fol-
lows is merely an indication of a possible way to arrange the material. It
begins with a defi nition and periodization of natural philosophy. These
suggest a development in the shape of an hourglass, the long axis repre-
senting time increasing downward and the cross section the correspond-
ing breadth of natural philosophy. The widest part at the top stands for
the situation during the last decades of the seventeenth century; the con-
striction in the middle, the situation in the decades around 1750; and the
progressive widening at the bottom, the years 1770–1815. The analogy
limps in many ways, perhaps most grievously in suggesting that natural
philosophy returned in 1800 to the same responsibilities it had a hundred
years earlier. The two states differed greatly in coverage as well as in con-
tent. The image of the hourglass has the merit, however, of emphasizing
that the later expansion of natural philosophy followed an earlier con-
striction, during which it lost its traditional connections within the body
of knowledge.
The beginning of the expansion dates from around 1770. At its end
around 1815, natural philosophy had taken on many of the traits of clas-
sical physics. The reasons for and nature of the infl ection around 1770
thus have a strong claim on the historian of science. The forces at play in
forming modern science—the interests of nation- states, individual entre-
CHAPTER 7Natural Philosophy
John L. Heilbron