LIMITING FACTORS IN THE HISTORY OF SCIENCE 



Galen, and may be compared with the following passage^ from the 

 latter writer's Commentary on Hippocrates: "We teach that some parts 

 of the body are formed from the semen and the flesh alone from 

 blood. But because the amount of semen which is injected into the 

 uterus is small, growth and increment must come for the most part 

 from the blood." It might thus appear that, just as the Jews of Alex- 

 andria were reading Aristotle in the third century B.C. and incorporat- 

 ing him into the Wisdom Literature, so those of the third century 

 A.D. were reading Galen and incorporating him into the Talmud. 



But we must beware here of suffering a distortion of perspective in 

 the contemplation of antiquit}^, for it is easy to exaggerate the co- 

 operation of ancient thought. A single idea could consider itself 

 lucky if it passed once in twenty-five years between Greece and India 

 after Alexander. Among the conflicting influences that gave rise to 

 the civilisation of the later West, this co-operation, hampered by 

 enormous linguistic difficulties on the one hand and by the diversion 

 of interest from scientific to ethical and theological channels on the 

 other, sank to a very low level. Hence we have the remarkable 

 spectacle of a Leonardo, many years ahead of his contemporaries, 

 and able to earn a living only as a designer of fortifications, finding 

 it impossible to communicate his discoveries to any living person, 

 and reduced to burying them in note-books,^ only by a mere chance 

 available to scholars of after ages. 



Scientific Technique. 



Among the most important of limiting factors we must reckon 

 Technique, extending the term to cover mental as well as material 

 methodology. The part which the latter has played in the history of 

 embryology can hardly be overrated. Thus until the introduction of 

 hardening agents, especially alcohol, by Boyle,^ the examination of 

 the early stages of embryos was bound to remain crude, and embry- 

 ology attained an entirely different level immediately afterwards, in 

 the hands of Maitre-Jan.^ The parallel case of the microscope is too 

 familiar to dwell on, but the work of Malpighi obviously marked a 



^ Ten centuries later it was still worth while for Harvey to have a hit at this opinion. 

 "In the interim," he says (1653, p. 116), "we canot chuse but smile at that fond and 

 fictitious Division of the Parts into Spermatical and Sanguineous; as if any part were 

 immediately framed of the semen, and were not all of one extract and original." 



2 QuaJerni d'Anatomia, ed. Vangensten, Fohnahn & Hopstock (Copenhagen, 191 1). 



^ Phil Trans. Roy. Soc, 1666, 1, 199. 



* Observations sur la formation du Poulet, etc.^ ij22. 



