PREFACE v 



the facts concerned, the way in which they are approached, 

 and the degree and character of the certainty attained. 

 The second of these two plans was the one chosen. 

 Professor Sherrington illustrates by an account of the 

 problem of the warmth of the body his description of 

 Physiology 'as the study of the working of living things'. 

 Professor Weldon shows the difficulties with which the 

 student has to contend who aims at giving an accurate 

 and trustworthy interpretation of the facts involved in 

 Inheritance. Mr. McDougall explains, by means of an 

 account of the methods of determining the mode and 

 duration of the perception of light, some of the ways in 

 which it is attempted to bring scientific accuracy into the 

 region of psychical phenomena under the head of non-ex- 

 perimental sciences. Dr. Fison shows how the methods 

 of physics may be used to explain phenomena observed in 

 stars far beyond the reach of the finest telescope. In the 

 other three Lectures we deal with the phenomena pre- 

 sented by man in his history in the world. Sir Richard 

 Temple by his sketch of the development of currency 

 shows how principles, which we all still apply and under- 

 stand, have developed in logical order, and have operated 

 in the whole history of man. Professor Flinders Petrie 

 shows how man registers the history of his own social 

 development, unconsciously in the things he makes and 

 uses and leaves behind him when he dies. And in the 

 last Lecture an attempt is made to show upon what we 

 rest our confidence in history, when ' material history ' 

 fails us. 



It is obvious that in a course like this the whole ground 



