negative tone, and treats the very conception of studying Logic
otherwise than in its applications as chimerical. He got on, in his
subsequent writings, to considering it as wrong. This indispensable part
of Positive Philosophy he not only left to be supplied by others, but
did all that depended on him to discourage them from attempting it.

This hiatus in M. Comte's system is not unconnected with a defect in his
original conception of the subject matter of scientific investigation,
which has been generally noticed, for it lies on the surface, and is
more apt to be exaggerated than overlooked. It is often said of him that
he rejects the study of causes. This is not, in the correct acceptation,
true, for it is only questions of ultimate origin, and of Efficient as
distinguished from what are called Physical causes, that he rejects. The
causes that he regards as inaccessible are causes which are not
themselves phaenomena. Like other people he admits the study of causes,
in every sense in which one physical fact can be the cause of another.
But he has an objection to the _word_ cause; he will only consent to
speak of Laws of Succession: and depriving himself of the use of a word
which has a Positive meaning, he misses the meaning it expresses. He
sees no difference between such generalizations as Kepler's laws, and
such as the theory of gravitation. He fails to perceive the real
distinction between the laws of succession and coexistence which
thinkers of a different school call Laws of Phaenomena, and those of
what they call the action of Causes: the former exemplified by the
succession of day and night, the latter by the earth's rotation which
causes it. The succession of day and night is as much an invariable
sequence, as the alternate exposure of opposite sides of the earth to
the sun. Yet day and night are not the causes of one another; why?
Because their sequence, though invariable in our experience, is not
unconditionally so: those facts only succeed each other, provided that