117 
These observations, however, remained unfruitful, and it was 
the great merit of Lavoisier that he applied the balance to all 
chemical phenomena, and established chemistry as an exact 
science. Since his time chemistry has continually extended its 
discoveries and its triumphs; never abandoning the solid and 
sure ground I have indicated, that of weight and measure; but 
advancing its empire like the Romans, notwithstanding frequent 
defeats, and the abandonment of one theory after another, in 
obedience to the stern logic of fact. 
Now Tyndall looks upon Descartes, who did not believe in 
atoms at all, as one of the two restorers of (atomic ?) philosophy, 
and “ the first to reduce, in a manner eminently capable of bear- 
ing the test'" (not of the balance, but) “ of mental presentation, 
vital •phenomena to purely mechanical principles ! ” * 
“Insight” then, and not “ weight and measure is the real 
test which is valuable in the sight of Tyndall ; and dogma, and 
not Science, is the result. 
But to extend the dominion of (supposed) chemical theory 
into the region of metaphysics, as in the Address at Belfast, is 
nothing less than treason against chemistry, and crime de Use 
majeste against common sense ! 
It would be well if some of our philosophers would study 
Democritus in the rules which he proposes for the acquisition of 
peace of mind (evQupia) as the end and ultimate object of our 
actions. 
“ Abstinence from too many occupations, a steady consideration of one’s 
own powers, which prevents our attempting that which we cannot accom- 
plish ; ” f 
these are some of the means which he proposes for this end. 
Democritus had a sufficient amount of common sense to under- 
stand that the soul is somehow altogether different from the body, 
and therefore he made the soul consist of fine, smooth, round 
atoms, like those of fire. “ These are the most mobile of all. They 
inter-penetrate the whole body, and in their motions the pheno- 
mena of life arise . 11 
This, the Professor indicates, arose from his not understanding 
the nervous system , % “ whose functions were then unknown.” 
He told us fourteen years ago, in the Saturday Review, 
“ that every thought and every feeling has its definite mechanical 
correlative in the nervous system — that it is accompanied by a 
* Address p. 21, and compare Appendix, 
+ Smith’s Dictionary of Biography , &c., sub voce. 
t Address, p. 5. 
