REVIEWS — MATHEMATICAL AND PHYSICAL SCIENCE. 367 



For, in the first place, to write the history of azvy particular branch, 

 the historian must have himself thoroughly mastered it ; no mere 

 dilettante or second-hand knowledge will save him from error on the 

 one hand, or plagiarism on the other : however difficult or complicated 

 the process by which an idea has been developed or result arrived at, 

 it is essential that he go through it in all its details before he can ven- 

 ture to deviate from the form of words in which his predecessors or 

 the author himself may have presented it. He is conscious also that 

 his performance must bear the criticism of those who have made that 

 department their especial study, and his knowledge is thus to be guaged 

 by the standard, not of the average, but of the highest. When we 

 consider the vast range and variety of direction, in which modern 

 philosophy is sweeping, this requirement assumes alarming proportions, 

 and, if to it we superadd the further difficulty of expressing scientific 

 results in such language that he who runs may read — of stating in 

 familiar words what is perhaps hard enough to understand in its pro- 

 per technical form, we can hardly wonder that so few attempts have 

 been made at thus writing the histories of even the separate physical 

 sciences — much less that of the whole of them — and that scarcely any 

 have been successful. 



If the universal suffrage of the British scientific world had been 

 taken, we believe it would have unanimously pointed out Professor 

 Forbes of Edinburgh, as the man of all others (excepting only the 

 illustrious author of the " History of the Inductive Sciences") most em- 

 inently fitted for the task, and the Dissertation, above cited, would 

 have been a triumphant confirmation of their vote. Holding a prom- 

 inent position in his University, and distinguished for original research 

 in some special departments, Professor Forbes has been long known for 

 one of the very few who have kept up their knowledge to th,e level of 

 the general advance of philosophy throughout its whole extent, so far 

 as may be done within the limits of human life and power. The work 

 before us is in every respect worthy of his reputation, and we should 

 find it hard to express our opinion of it in terms of praise which would 

 not appear extravagant to persons whose perception of the excellence 

 of the performance is not enhanced by a full appreciation of its diffi- 

 culty. Regarding the work in its strictly scientific aspect, it becomes 

 a reviewer to speak with diffidence, nor do we affect to be able to criti- 

 cise all that is set down : we would only say, that in the departments 

 with which we are most familiar, we have tracked our author minutely 

 and rigorously, and that we have detected no inaccuracy of statement, 

 no ambiguity of phrase by which a difficulty might be conveniently 

 slurred over, none of those little slips which so often in " popular " 



