BOOK I PART II
or right ones. But though we can give no per-
fect definition of these lines, nor produce any
very exact method of distinguishing the one
from the other; yet this hinders us not from cor-
recting the first appearance by a more accurate
consideration, and by a comparison with some
rule, of whose rectitude from repeated trials we
have a greater assurance. And it is from these
corrections, and by carrying on the same action
of the mind, even when its reason fails us, that
we form the loose idea of a perfect standard to
these figures, without being able to explain or
comprehend it.
It is true, mathematicians pretend they give
an exact definition of a right line, when they
say, it is the shortest way betwixt two points.
But in the first place I observe, that this is more
properly the discovery of one of the proper-