48 GENERAL PREFACE TO 



simply in virtue of the classification employed. For this axiom, 

 if true, properly belongs to physiology, and neither to perspec- 

 tive nor to acoustics ; though in a secondary and derivative 

 manner a portion of the truth it includes may be introduced 

 into these sciences. And so on. There is however one of these 

 axioms which is of higher authority : " Quantum naturae nee 

 minuitur nee augetur:" which, Bacon says, is true not only 

 in physics, but also in natural theology, if it be stated in a 

 modified form; viz. if it be said that it belongs to Omnipo- 

 tence to make something out of nothing, or vice versa. Of 

 this axiom it may be remarked, that it is common to physics 

 and natural theology simply because the subjects of these 

 sciences are, in some measure, common to both; wherein it 

 differs from the Aristotelian conception of an axiom. But it is 

 of more interest to observe, that this axiom of which the truth 

 is derived from our notion of substance, and which can never be 

 established by an empirical demonstration, is constantly quoted 

 by Bacon as a principle of incontestable truth ; of which his 

 theory of specific gravities is in some sort only an application. 

 The question arises both with regard to this axiom and to 

 the others, In what manner Bacon supposed that they ought to 

 be demonstrated ; or, if he thought they required no demonstra- 

 tion, in what manner he conceived that the mind apprehended 

 their truth ? He has certainly affirmed in express terms that 

 there can be only two ways of arriving at truth, namely syllo- 

 gism and induction ; both of which are manifestly inapplicable 

 to some at least of the principles which he includes in the 

 philosophia prima. But whether he would have admitted that 

 this dictum admits of exception in relation to these cases, or on 

 the other hand had not been led to consider the nature of the 

 difficulty which they present, we have, I think, no means of 

 deciding. It is to be observed that the philosophia prima is 

 spoken of as a collection (receptaculum) of axioms a phrase 

 which implies that it is not a science in itself, having its own 

 principles and an independent development, but that, contrari- 

 wise, it derives from the contributions of other sciences the 

 elements of which it is composed. Of the second part we are 

 unable to speak more definitely than of the first. It is obviously 

 a reflexion of the Aristotelian doctrine of the categories ', from 



1 Trendelenberg has accordingly quoted the passages in the De Avgmentis which 

 relate to it, in the historical part of his work on the categories. 



