MATTER IN MOTION 91 



day dictates, and sometimes he may even intro- 

 duce irrelevant arguments for a similar reason. 

 Can we believe that Jean Rey,^ who first an- 

 nounced clearly the law of conservation of mass, 

 was himself convinced by the argument that he 

 offered to the public?: "Let there be taken a 

 portion of earth which shall have in it the small- 

 est possible weight, beyond which no weight 

 can subsist: let this earth be converted into 

 water by the means known and practised by 

 nature; it is evident that this water will have 

 weight, since all water must have it, and this 

 weight will either be greater than that of the 

 earth, or less than it, or else equal to it. My 



2 Jean B.ey, The Increase in Weight of Tin and Lead on 

 Calcination (1630). Alembic Club Reprints. There are so 

 many gibes at the lack of modesty among scientific men 

 to-day that I cannot resist quoting the conclusion of Rey's 

 extremely important paper. 



"Behold now this truth, whose brilliance strikes the eye, 

 which I have drawn from the deepest dungeons of obscu- 

 rity. This it is to which the path has been hitherto inac- 

 cessible. This it is which has distressed with toil so many 

 learned men, who, wishing to know it, have striven to clear 

 the diflBculties which held it encircled. Cardan, Scaliger, 

 Fachsius, Caesalpinus, Libavius, have curiously sought it, 

 but never perceived it. Others may be on its quest, but 

 vainly if they fail to follow the road which I first of all 

 have made clear and royal: all others being but thorny 

 footpaths and inextricable byways which lead never to the 

 goal. The labour has been mine; may the profit be to the 

 reader, and to God alone the glory." 



