56 Introduction 



completed by Georg Cantor ( 1845-1918). It is always the same thing. 

 We only see what we already know, hence our appreciation of the past 

 changes as the future unrolls. Scholars of the seventeenth century who 

 were more familiar with the Greek language than we are could not un- 

 derstand Greek science as well as we do, but our knowledge of it is 

 not by any means completed. As to mediaeval science, we are only 

 beginning to appreciate its true value without exaggeration of praise or 

 disparagement. The darkness of the Dark Ages of which uneducated 

 scientists speak so glibly is partly the darkness of their own ignorance 

 and unwisdom. 



Now to return to my own experience. After many tentatives in var- 

 ious directions, such as an attempt to review the whole field in a single 

 course ( of, say, thirty-five lectures ) or of dealing within the same orbit 

 with a relatively brief period (say, the Renaissance) or with a single 

 branch of science ( say, mathematics or physics ) , I have come to the con- 

 clusion that the needs of honest students in a good college are satisfied 

 best with the following arrangement. My general course on the history 

 of science is a combination of four courses of about thirty-five lectures 

 each, dealing respectively with (i) antiquity, (2) Middle Ages, (3) the 

 fifteenth, sixteenth and seventeenth centuries, (4) the eighteenth and 

 nineteenth centuries with glimpses of the twentieth. These courses are 

 independent. Few students attend the four of them, and fewer still are 

 able to take them in the proper order. Classical students may take only 

 the first, mediaevalists only the second, scientific students only the third 

 and fourth or only the fourth. I offer only two such courses each year, 

 never more, but sometimes less. Hence, two years at least will elapse 

 before I come back to the same subject.*'^ This interval is long enough 

 to make possible a partial renewal not only of that subject but of myself. 



To be sure, each of these courses is a summary, but it is perhaps of 

 sufficient length to satisfy the majority of the students and to encourage 

 a few of them to go ahead and seek more knowledge either with my help 

 or without. Consider the case of ancient science. I doubt whether it 

 would be possible to give a fair idea of its richness and diversity and to 

 place it clearly in its cultural background in much less than thirty or 

 thirty-five lectures. One must devote one lecture to the pre-historic 

 beginnings, two or three more to Egyptian and Babylonian antiquities. 

 (This is running at full speed. ) There remain then some thirty lectures, 

 or less, for the whole of Hellenic, Hellenistic and Roman culture, from 

 Homer down to Proclos, a stretch of at least fourteen centuries. Dur- 

 ing those centuries, not only did science develop in many directions but 

 the cultural, philosophical, social, and religious background was con- 

 stantly modified. Whenever I try to explain such momentous changes 

 in thirty lectures, I cannot help feeling that my speed is dangerous. A 

 little more speed and everything would vanish. The survey would be- 

 come almost meaningless. This is the more true, because a great num- 



** Not necessarily to every subject, for the contents of each course varies somewhat 

 from each offering to the next one. As the total of lectures is fixed, it is not possible 

 to introduce a new subject without dropping an old one. 



