Matter and Force. He objected to the use of the term atom:--'I have
not yet found a mind,' he says, 'that did habitually separate it
from its accompanying temptations; and there can be no doubt that
the words definite proportions, equivalent, primes, &c., which did
and do fully express all the facts of what is usually called the
atomic theory in chemistry, were dismissed because they were not
expressive enough, and did not say all that was in the mind of him
who used the word atom in their stead.'

A moment will be granted me to indicate my own view of Faraday's
position here. The word 'atom' was not used in the stead of
definite proportions, equivalents, or primes. These terms
represented facts that followed from, but were not equivalent to,
the atomic theory. Facts cannot satisfy the mind: and the law of
definite combining proportions being once established, the question
'why should combination take place according to that law?' is
inevitable. Dalton answered this question by the enunciation of the
Atomic Theory, the fundamental idea of which is, in my opinion,
perfectly secure. The objection of Faraday to Dalton might be urged
with the same substantial force against Newton: it might be stated
with regard to the planetary motions that the laws of Kepler
revealed the facts; that the introduction of the principle of
gravitation was an addition to the facts. But this is the essence
of all theory. The theory is the backward guess from fact to
principle; the conjecture, or divination regarding something, which
lies behind the facts, and from which they flow in necessary
sequence. If Dalton's theory, then, account for the definite
proportions observed in the combinations of chemistry, its
justification rests upon the same basis as that of the principle of
gravitation. All that can in strictness be said in either case is