74 INTRODUCTION TO SCIENCE 



old, some reconsideration of the one or the other, 

 or of both, will be necessary. ' 



Lord Kelvin was wont to emphasize the dis- 

 tinction between two stages of progress in science, 

 the "Natural History" stage and the "Natural 

 Philosophy" stage. In his introductory lecture 

 (1846) as Professor of Natural Philosophy in 

 Glasgow University a lecture which he repeated 

 for over fifty years he said: "In the progres- 

 sive study of natural phenomena, that is, the 

 phenomena of the external world, the first work 

 is to observe and classify facts; the process of 

 inductive generalization follows, hi which the 

 laws of nature are the objects of research. These 

 two stages of science are designated by the ex- 

 pressions' of natural history and natural philos- 

 ophy." In other words, there is an observational 

 and descriptive stage, followed by generaliza- 

 tion and formulation. 



It is necessary, then, to make a clear distinc- 

 tion between the raw materials of science and 

 the systematizations which raise these to a 

 higher power. As Prof. P. G. Tait once said: 

 "Descriptive botany, natural history, volumes 

 of astronomical observations, etc., are collec- 

 tions of statements, often facts, from which 

 scientific truth may ultimately be extracted, but 

 they are not science. Science begins to dawn, 

 but only to dawn, when a Copernicus, and after 



