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sense ; or, in other words, that of the condensed experience of 
mankind. The second is that of the profoundest philosophy. 
15. It was reserved for another deep thinker to bring the 
admirable speculations of Newton within the domain of facts. 
It is by weight and measure that we realise our conceptions of 
body, about which sight unaided does not always give us 
accurate information. What we think we see is not always 
really seen; and much as we owe to spectrum analysis in 
assisting in the investigation of the properties of matter, we 
are yet not able to obtain the amount of certainty which 
attends the following research. 
16. It was Dalton, then, who first gave the idea of atomic 
weights : — (C It was by a careful mechanical juxtaposition of 
parts that Dalton arrived at the idea : it is eminently 
mechanical, and it is remarkable that all progressive views on 
the subject have been so. He introduced proportional weights 
into the theory , and found it to agree with facts. His is, there- 
fore, the quantitative atomic theory.”* 
17. Taking advantage of the already ascertained property 
of a mass of matter, called the attraction of gravitation, 
indicated by the weights in the balance, he thus enabled us to 
understand correctly something more about the intimate 
properties of body or substance, giving a solid basis to that 
which was previously theory. 
18. The notion of the atomic constitution of matter formed 
part of the philosophy of the Hindoos, Phoenicians, and 
Egyptians, and must, in all probability, have descended to 
them from a very early antiquity, when those nations could 
share in common ideas. 
19. Amongst the Greeks it afforded the basis of the 
cosmogony of Democritus ; and, subsequently, Epicurus and 
the Epicureans generally supported the atomic hypothesis ; 
and in a most admirable poem, Lucretius discourses on the 
nature of things in a sense hostile to religion, or, rather, to the 
abominable superstition which alone was to him “ Religio,” — 
“ Tantum Eeligio potuit suadere malorum.”+ 
20. Hence, I suppose, arose the prevalent opinion of the 
atheistic tendency of the doctrine which he inculcated. But 
if any person can read the poet's description of the sacrificed 
Iphigenia without partaking in his indignation, he must be 
destitute of humanity. We must needs, in so far, sympathise 
* TJre’s Dictionary , vol. iii. p. 270. 
t Lucretius, lib. i., 1. 90. 
