A Treatise of Human Nature HTML version

because they are removed beyond that distance, at which their impressions were reduced
to a minimum, and were incapable of any farther diminution. A microscope or telescope,
which renders them visible, produces not any new rays of light, but only spreads those,
which always flowed from them; and by that means both gives parts to impressions,
which to the naked eye appear simple and uncompounded, and advances to a minimum,
what was formerly imperceptible.
We may hence discover the error of the common opinion, that the capacity of the mind is
limited on both sides, and that it is impossible for the imagination to form an adequate
idea, of what goes beyond a certain degree of minuteness as well as of greatness. Nothing
can be more minute, than some ideas, which we form in the fancy; and images, which
appear to the senses; since there are ideas and images perfectly simple and indivisible.
The only defect of our senses is, that they give us disproportioned images of things, and
represent as minute and uncompounded what is really great and composed of a vast
number of parts. This mistake we are not sensible of: but taking the impressions of those
minute objects, which appear to the senses, to be equal or nearly equal to the objects, and
finding by reason, that there are other objects vastly more minute, we too hastily
conclude, that these are inferior to any idea of our imagination or impression of our
senses. This however is certain, that we can form ideas, which shall be no greater than the
smallest atom of the animal spirits of an insect a thousand times less than a mite: And we
ought rather to conclude, that the difficulty lies in enlarging our conceptions so much as
to form a just notion of a mite, or even of an insect a thousand times less than a mite. For
in order to form a just notion of these animals, we must have a distinct idea representing
every part of them, which, according to the system of infinite divisibility, is utterly
impossible, and, recording to that of indivisible parts or atoms, is extremely difficult, by
reason of the vast number and multiplicity of these parts.
Wherever ideas are adequate representations of objects, the relations, contradictions and
agreements of the ideas are all applicable to the objects; and this we may in general
observe to be the foundation of all human knowledge. But our ideas are adequate
representations of the most minute parts of extension; and through whatever divisions and
subdivisions we may suppose these parts to be arrived at, they can never become inferior
to some ideas, which we form. The plain consequence is, that whatever appears
impossible and contradictory upon the comparison of these ideas, must be really
impossible and contradictory, without any farther excuse or evasion.
Every thing capable of being infinitely divided contains an infinite number of parts;
otherwise the division would be stopt short by the indivisible parts, which we should
immediately arrive at. If therefore any finite extension be infinitely divisible, it can be no
contradiction to suppose, that a finite extension contains an infinite number of parts: And
vice versa, if it be a contradiction to suppose, that a finite extension contains an infinite
number of parts, no finite extension can be infinitely divisible. But that this latter
supposition is absurd, I easily convince myself by the consideration of my clear ideas. I
first take the least idea I can form of a part of extension, and being certain that there is