rformed already,
there are two reasons why its repetition here may not be without
utility: for, first, its subject is a treatise containing the germs of
much subsequent and still current speculation which, in so far as it is
merely a development of those germs, cannot but be infected by whatever
unsoundness may be inherent in them; and, secondly, because the subject,
hackneyed as it may seem, is so far from being exhausted, that there is
scarcely one among the doctrines embodied in it to which, as I proceed
at once to show, fresh objection, more or less grave, may not be taken
by a fresh investigator.

To begin very near indeed to the beginning, let us take, first, the
section of the 'Enquiry' which treats of the 'Origin of Ideas.' All the
perceptions of the mind may, according to Hume, be divided into two
classes, whereof the one consists of all those 'more lively
perceptions,' termed by him indifferently Impressions or Sensations,
which we experience when we 'hear, or see, or feel, or love, or hate, or
desire, or will:' the other, of those 'less lively perceptions of which
we are conscious when we reflect on any of the sensations
above-mentioned,' and which are commonly denominated thoughts or ideas.
'All our ideas or more feeble perceptions,' he continues, 'are copies of
our impressions or more lively ones,' the 'entire creative power of the
mind amounting to no more than the faculty of compounding, transposing,
augmenting, or diminishing the materials afforded by the senses and
experience.' So confident is he of the literal accuracy of this
statement, as to proceed to intimate that whenever we find in
conversation or argument 'a philosophical term employed seemingly
without any idea or meaning,' we have only to enquire from what
impression its idea, if it have one, is derived, when, if no impression
can be adduced, we may be sure that no idea is present either. The only
phenomenon opposed to this rule, which he professes himself able to
think of, is that of a person who, of a colour--as, for instance,
blue--with which he is familiar, is able to conceive a shade somewhat
different from any of the shades which he has actually seen; but this
instance he disregards as too singular to affect the general maxim, to
which, as he might have added, it is not really an exception, any more
than would be the power of a person who had never seen a mountain higher
than Snowdon or Mont Blanc to conceive one as high as Chimborazo or