ns, 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
antecedent. This is the only part of Hume's doctrine which was contested
by his great adversary, Kant; who, maintaining as strenuously as Comte
that we know nothing of Things in themselves, of Noumena, of real
Substances and real Causes, yet peremptorily asserted their existence.
But neither does Comte question this: on the contrary, all his language
implies it. Among the direct successors of Hume, the writer who has best
stated and defended Comte's fundamental doctrine is Dr Thomas Brown. The
doctrine and spirit of Brown's philosophy are entirely Positivist, and
no better introduction to Positivism than the early part of his Lectures
has yet been produced. Of living thinkers we do not speak; but the same
great truth formed the groundwork of all the speculative philosophy of
Bentham, and pre-eminently of James Mill: and Sir William Hamilton's
famous doctrine of the Relativity of human knowledge has guided many to
it, though we cannot credit Sir William Hamilton himself with having
understood the principle, or been willing to assent to it if he had.

The foundation of M. Comte's philosophy is thus in no way