BOOK I PART II
that give us a true idea of extension. The sen-
sation of motion is likewise the same, when
there is nothing tangible interposed betwixt
two bodies, as when we feel a compounded
body, whose different parts are placed beyond
each other.
Secondly, We find by experience, that two
bodies, which are so placed as to affect the
senses in the same manner with two others,
that have a certain extent of visible objects in-
terposed betwixt them, are capable of receiv-
ing the same extent, without any sensible im-
pulse or penetration, and without any change
on that angle, under which they appear to the
senses. In like manner, where there is one ob-
ject, which we cannot feel after another without
an interval, and the perceiving of that sensation
we call motion in our hand or organ of sensa-