There is, for instance, a well known way of showing that the area of a circle bears the same relation to the area of an ellipse, the major axis of which is the diameter of the circle, as the major axis does to the minor axis, by taking each of these areas as the sum of the ordinates pertaining to it; each ordinate of the ellipse stands to the corresponding ordinate of the circle as the minor axis stands to the major; therefore, it is concluded, also the sums of the ordinates, that is, the areas, stand in equal proportion.