sought for the cause, it was mainly in order to control the effect or if
it was uncontrollable, to foreknow and adapt their conduct to it. Now,
all foresight of phaenomena, and power over them, depend on knowledge of
their sequences, and not upon any notion we may have formed respecting
their origin or inmost nature. We foresee a fact or event by means of
facts which are signs of it, because experience has shown them to be its
antecedents. We bring about any fact, other than our own muscular
contractions, by means of some fact which experience has shown to be
followed by it. All foresight, therefore, and all intelligent action,
have only been possible in proportion as men have successfully attempted
to ascertain the successions of phaenomena. Neither foreknowledge, nor
the knowledge which is practical power, can be acquired by any other
means.

The conviction, however, that knowledge of the successions and
co-existences of phaenomena is the sole knowledge accessible to us,
could not be arrived at in a very early stage of the progress of
thought. Men have not even now left off hoping for other knowledge, nor
believing that they have attained it; and that, when attained, it is, in
some undefinable manner, greatly more precious than mere knowledge of
sequences and co-existences. The true doctrine was not seen in its full
clearness even by Bacon, though it is the result to which all his
speculations tend: still less by Descartes. It was, however, correctly
apprehended by Newton.[1]

But it was probably first conceived in its entire generality by Hume,
who carries it a step further than Comte, maintaining not merely that
the only causes of phaenomena which can be known to us are other
phaenomena, their invariable antecedents, but that there is no other
kind of causes: cause, as he interprets it, _means_ the invariable