BOOK I PART II
pearances and measuring are exactly corrected,
and the figures reduced entirely to that propor-
tion. This standard is plainly imaginary. For
as the very idea of equality is that of such a
particular appearance corrected by juxtaposi-
tion or a common measure. The notion of any
correction beyond what we have instruments
and art to make, is a mere fiction of the mind,
and useless as well as incomprehensible. But
though this standard be only imaginary, the fic-
tion however is very natural; nor is anything
more usual, than for the mind to proceed af-
ter this manner with any action, even after the
reason has ceased, which first determined it to
begin. This appears very conspicuously with
regard to time; where though it is evident we
have no exact method of determining the pro-
portions of parts, not even so exact as in ex-
tension, yet the various corrections of our mea-