rely, by the hypothesis, a movement
between two stops; if there are intermediate stops, it is no longer a
single movement. At bottom, the illusion arises from this, that the
movement, _once effected_, has laid along its course a motionless
trajectory on which we can count as many immobilities as we will. From
this we conclude that the movement, _whilst being effected_, lays at
each instant beneath it a position with which it coincides. We do not
see that the trajectory is created in one stroke, although a certain
time is required for it; and that though we can divide at will the
trajectory once created, we cannot divide its creation, which is an act
in progress and not a thing. To suppose that the moving body _is_ at a
point of its course is to cut the course in two by a snip of the
scissors at this point, and to substitute two trajectories for the
single trajectory which we were first considering. It is to distinguish
two successive acts where, by the hypothesis, there is only one. In
short, it is to attribute to the course itself of the arrow everything
that can be said of the interval that the arrow has traversed, that is
to say, to admit _a priori_ the absurdity that movement coincides with
immobility.

We shall not dwell here on the three other arguments of Zeno. We have
examined them elsewhere. It is enough to point out that they all consist
in applying the movement to the line traversed, and supposing that what
is true of the line is true of the movement. The line, for example, may
be divided into as many parts as we wish, of any length that we wish,
and it is always the same line. From this we conclude that we have the
right to suppose the movement articulated as we wish, and that it is
always the same movement. We thus obtain a series of absurdities that
all express the same fundamental absurdity. But the possibility of
applying the movement _to_ the line traversed exists only for an
observer who keeping outside the movement and seeing at every instant
the possibility of a stop, tries to reconstruct the real movement with
these possible immobilities. The absurdity vanishes as soon as we adopt
by thought the continuity of the real movement, a continuity of which
every one of us is conscious whenever he lifts an arm or advances a
step. We feel then indeed that the line passed over between two stops is
described with a single indivisible stroke, and that we seek in vain to
practice on the movement, which traces th