In every arithmetic triangle, if two cells are contiguous in the same base, the upper is to the lower as the number of cells from the upper to the top of the base is to the number of those from the lower to the bottom inclusive.
(Pascal called positions in the same vertical column, in Fig. 15.12, “cells of the same perpendicular rank,” and those in the same horizontal row “cells of the same parallel rank”; cells in the same upward-sloping diagonal he called “cells of the same base.”)
Can someone explain this to me what is he saying.