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Proceedings of the Boyal Society 
tions of Thales and other philosophers of the Ionic school six 
hundred years before Christ, and to the more profound views of 
the Eleatic school, which had its origin about fifty years later, and 
the questioning which then arose regarding the reality of the know- 
ledge given us by the senses. 
Hume, by ingenious arguments, endeavoured to throw distrust on 
all human knowledge, and to show that we could neither prove the 
existence of power, the connection of cause and effect, nor the 
existence of an external world. Kant, roused by this, undertook 
to prove that the mind had certain judgments and beliefs, irrespec- 
tive of those derived from our connection with the world. This set 
the G-erman thinkers upon an exhaustive examination of mental 
phenomena, and led to the idealism so prevalent in G-erman phi- 
losophy. 
Disregarding, however, the extreme views of a numerous class 
of idealists, the question still remains open before us. What is 
matter ? 
The phenomena met with in prosecuting chemical science are 
frequently so marvellous and unexpected as to raise in the mind ol 
an abstract thinker doubts as to the theory that the atoms with 
which he is dealing are material atoms. The idea of matter or 
substance implies to every man who considers it abstractly the pos- 
session of certain qualities inherent in each substance. This idea is 
found, however, to be the reverse of a true one. The most trifiing 
difference in the proportions in which substances are combined fre- 
quently creates the most entire change of property. Witness the 
results of the various combinations of oxygen with carbon, with 
hydrogen, or with nitrogen, and witness the still more surprising ani- 
mal and vegetable productions which result from the united com- 
bination of these four elements — the oils, the gums, the dies, the 
fiesh, the vegetables, the medicines, the poisons, — in fact, nearly 
the entire catalogue of animal and vegetable products and prin- 
ciples with which we are acquainted. Quinine is composed of seventy 
atoms of these four elements, and so is strychnine, the only differ- 
ence being that the poison has two atoms more of carbon, and two 
less of hydrogen, than the tonic. All such facts indicate that the 
ultimate elements and their combinations act dynamically, for they 
do not act according to the way we would expect substances to act. 
