390 ELEMENTS OF SCIENCE 



that we can know the system of the relativity of know- 

 ledge to be true, he who so asserts proclaims that some 

 of our knowledge must be absolute ; but this upsets the 

 foundation of his whole system. 



Any one who upholds such a system as this, may be 

 compared to a man seated high up on the branch of a 

 tree, which he is engaged in sawing across where it 

 springs from the tree's trunk. The position and occupa- 

 tion of such a man can hardly be considered as evidence 

 of wisdom on his part. 



The simple but fundamental truths to which attention 

 has been called in this chapter, are really present in the 

 mind of every rational man, though they may be un- 

 observed or very imperfectly apprehended by him. They 

 have most important and far-reaching consequences, 

 and merit the attention of every one who desires to 

 be able to give a reasonable account of the convic- 

 tions of his own mind. They are truths which are 

 latent in, and so necessary for the validity of, every 

 branch of science, that any real doubt about them 

 would make not only experiment, but even observation, 

 logically impossible. 



The truths here put forward are, as before said, truths 

 of science par excellence, as distinguished from its various 

 branches with which we have been concerned in previous 

 chapters. They are truths of philosophy, and as tran- 

 scending evei^branch of "physics" constitute what we 

 call " metaphysics. 



But the student who^i^. perusing this chapter, meets 

 with ideas and reasoning with which he was before un- 

 familiar, must not imagine that by mastering them he 

 can acquire a knowledge of metaphysical truth or philo- 

 sophy. Some fragments of that truth he can thus 



