; and we shall find that this locus of points is what is meant by a straight line in the space of
. Thus the point
in the space of
correlates the successive points on a straight line of
with the successive moments of
; and we shall find that this locus of points is what is meant by a straight line in the space of
. Thus the point
in the space of
correlates the successive points on a straight line of
with the successive moments of