A Treatise of Human Nature

David Hume · en
I answer this objection, by pleading guilty, and by confessing that my
intention never was to penetrate into the nature of bodies, or explain
the secret causes of their operations. For besides that this belongs not
to my present purpose, I am afraid, that such an enterprise is beyond
the reach of human understanding, and that we can never pretend to
know body otherwise than by those external properties, which discover
themselves to the senses. As to those who attempt any thing farther, I
cannot approve of their ambition, till I see, in some one instance at
least, that they have met with success. But at present I content myself
with knowing perfectly the manner in which objects affect my senses, and
their connections with each other, as far as experience informs me of
them. This suffices for the conduct of life; and this also suffices for
my philosophy, which pretends only to explain the nature and causes of
our perceptions, or impressions and ideas.[6]

    [6] As long as we confine our speculations to the appearances of
    objects to our senses, without entering into disquisitions
    concerning their real nature and operations, we are safe from all
    difficulties, and can never be embarrassed by any question. Thus,
    if it be asked, if the invisible and intangible distance,
    interposed betwixt two objects, be something or nothing: It is easy
    to answer, that it is SOMETHING, VIZ. a property of the objects,
    which affect the SENSES after such a particular manner. If it be
    asked whether two objects, having such a distance betwixt them,
    touch or not: it may be answered, that this depends upon the
    definition of the word, TOUCH. If objects be said to touch, when
    there is nothing SENSIBLE interposed betwixt them, these objects
    touch: it objects be said to touch, when their IMAGES strike
    contiguous parts of the eye, and when the hand FEELS both objects
    successively, without any interposed motion, these objects do not
    touch. The appearances of objects to our senses are all consistent;
    and no difficulties can ever arise, but from the obscurity of the
    terms we make use of.