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Thus, if we accept the limitation of time placed before us by Sir 

 William Thomson, it is not obvious, on the face of the matter, 

 that we shall have to alter or reform our ways in any appreciable 

 degree, and we may therefore proceed with much calmness, and, 

 indeed, much indifference as to the result, to enquire whether that 

 limitation is justified by the argument employed in its support." He 

 then proceeds to investigate the arguments employed by Sir William, 

 and the data on which they are founded, and shows that they are 

 extremely doubtful. He has the following passage : — " Mathema- 

 tics may be compared to a mill of exquisite workmanship, which 

 grinds you stuff of any degree of fineness; but nevertheless, what 

 you get out depends on what you put in : and as the grandest mill 

 in the world will not extract wheat-flour from peas-cods, so pages 

 of formula will not get a definite result out of loose data." Varia- 

 tion ! natural selection ! time ! these are the elements with which 

 the Eternal has worked all through the mighty past. The first is the 

 most important, as it is the most mysterious. On it depends all the 

 rest. Without variation, natural selection and time could only 

 repeat the past. Variability is inherited. A living form that has 

 persisted long in one condition, by that very persistence is less 

 likely to vary in the future. One which has changed is more likely 

 to change again. Hence, the highest organisms are the most 

 variable, for in the past they have varied most. How rapid are 

 the changes with the mammals of the Tertiary epoch ! Man is 

 probably the most variable of all. Mr. Darwin quotes from papers 

 by Mr. J. Wood, published in the proceedings of the Royal So- 

 ciety, showing the extent of muscular variation in man. In a 

 single male subject, having a strong bodily frame and well-formed 

 skull, he found no less than seven muscular variations, all of which 

 plainly represented muscles proper to various kinds of apes. Mr. 

 Wood regards these variations as indicating some unknown factor 

 of much importance to a knowledge of general and scientific 

 anatomy. That unknown factor Mr. Darwin regards as reversion 

 to the form of some remote progenitor. That human beings vary 

 much is known to every father and mother of a family. No two 

 children are exactly alike in form, in disposition, or in capacity. 



