"A Treatise Concerning the Principles of Human Knowledge" - читать интересную книгу автора (Berkeley George)

6. In order to prepare the mind of the reader for the easier
conceiving what follows, it is proper to premise somewhat, by way of
Introduction, concerning the nature and abuse of Language. But the
unravelling this matter leads me in some measure to anticipate my
design, by taking notice of what seems to have had a chief part in
rendering speculation intricate and perplexed, and to have
occasioned innumerable errors and difficulties in almost all parts
of knowledge. And that is the opinion that the mind hath a power of
framing abstract ideas or notions of things. He who is not a perfect
stranger to the writings and disputes of philosophers must needs
acknowledge that no small part of them are spent about abstract ideas.
These are in a more especial manner thought to be the object of
those sciences which go by the name of Logic and Metaphysics, and of
all that which passes under the notion of the most abstracted and
sublime learning, in all which one shall scarce find any question
handled in such a manner as does not suppose their existence in the
mind, and that it is well acquainted with them.

7. It is agreed on all hands that the qualities or modes of things
do never really exist each of them apart by itself, and separated from
all others, but are mixed, as it were, and blended together, several
in the same object. But, we are told, the mind being able to
consider each quality singly, or abstracted from those other qualities
with which it is united, does by that means frame to itself abstract
ideas. For example, there is perceived by sight an object extended,
coloured, and moved: this mixed or compound idea the mind resolving
into its simple, constituent parts, and viewing each by itself,
exclusive of the rest, does frame the abstract ideas of extension,
colour, and motion. Not that it is possible for colour or motion to
exist without extension; but only that the mind can frame to itself by
abstraction the idea of colour exclusive of extension, and of motion
exclusive of both colour and extension.

8. Again, the mind having observed that in the particular extensions
perceived by sense there is something common and alike in all, and
some other things peculiar, as this or that figure or magnitude, which
distinguish them one from another; it considers apart or singles out
by itself that which is common, making thereof a most abstract idea of
extension, which is neither line, surface, nor solid, nor has any
figure or magnitude, but is an idea entirely prescinded from all
these. So likewise the mind, by leaving out of the particular
colours perceived by sense that which distinguishes them one from
another, and retaining that only which is common to all, makes an idea
of colour in abstract which is neither red, nor blue, nor white, nor
any other determinate colour. And, in like manner, by considering
motion abstractedly not only from the body moved, but likewise from
the figure it describes, and all particular directions and velocities,
the abstract idea of motion is framed; which equally corresponds to
all particular motions whatsoever that may be perceived by sense.