is possible to be known about atoms and molecules; so that if further
wonders should be evoked, the argument will grow and grow in cumulative
force.

Let me sum up the conclusion to be drawn from these facts in a quotation
from a discourse of Sir John F.W. Herschel.

"When we see," says that eminent philosopher, "a great number of things
precisely alike, we do not believe this similarity to have originated
except from _a common principle independent of them_; and that we
recognize this likeness, chiefly by the _identity of their deportment
under similar circumstances_ strengthens rather than weakens the
conclusion.

"A line of spinning jennies, or a regiment of soldiers dressed exactly
alike and going through precisely the same evolutions, gives us no idea
of independent existence: we must see them act out of concert before we
can believe them to have independent wills and properties not impressed
on them from without.

"And this conclusion, which would be strong even if there were only two
individuals precisely alike in _all_ respects and _for ever_, acquires
irresistible force when their number is multiplied beyond the power of
imagination to conceive.

"If we mistake not, then, the discoveries alluded to effectually destroy
the ideas of an _eternal_ self-existent matter by giving to each of its
atoms the essential characters at once of a _manufactured_ article and
of a _subordinate agent_."