The value of D at the point of the aggregate demand function, where it is intersected by the aggregate supply function, will be called the effective demand.

总需求函数与总供给函数相交点处的 D 值称为有效需求。

But, in the main, it is the part played by the aggregate demand function which has been overlooked; and it is to the aggregate demand function that we shall devote Books III and IV.

但是，总的来说，人们忽视了总需求函数所起的作用；我们将在第三卷和第四卷中讨论总需求函数。