from the mere removal of visible objects we receive the impression of
extension without matter; and that the idea of utter darkness can never
be the same with that of vacuum.

Suppose again a man to be Supported in the air, and to be softly conveyed
along by some invisible power; it is evident he is sensible of nothing,
and never receives the idea of extension, nor indeed any idea, from this
invariable motion. Even supposing he moves his limbs to and fro, this
cannot convey to him that idea. He feels in that case a certain sensation
or impression, the parts of which are successive to each other, and may
give him the idea of time: But certainly are not disposed in such a
manner, as is necessary to convey the idea of s ace or the idea of space
or extension.

Since then it appears, that darkness and motion, with the utter removal
of every thing visible and tangible, can never give us the idea of
extension without matter, or of a vacuum; the next question is, whether
they can convey this idea, when mixed with something visible and
tangible?

It is commonly allowed by philosophers, that all bodies, which discover
themselves to the eye, appear as if painted on a plain surface, and that
their different degrees of remoteness from ourselves are discovered more
by reason than by the senses. When I hold up my hand before me, and
spread my fingers, they are separated as perfectly by the blue colour of
the firmament, as they coued be by any visible object, which I coued
place betwixt them. In order, therefore, to know whether the sight can
convey the impression and idea of a vacuum, we must suppose, that amidst
an entire darkness, there are luminous bodies presented to us, whose
light discovers only these bodies themselves, without giving us any