then,
as the first term is to the second, so is the third to the fourth; and hence, by
alternation, as the first is to the third, so is the second to the fourth; and therefore
also, as the first is to the second, so is the sum of the first and third to the sum of
the second and fourth. Now this is the combination effected by a distribution of shares,
and the combination is a just one, if persons and shares are added together in this way.