21. All Positions lying in the same direction and at the same distance
from a given point, taken as a premise-point, are one. There is no such
thing, therefore, as a Harmony of Positions. Positions in Harmony are
identical positions. Two or more positions may, however, lie in the
same direction from or at the same distance from a given point taken
as a premise-point. In that case, the two or more positions, having a
direction or a distance in common, are, to that extent, in harmony.