such as they could afford to pay.


§2. _Diagrams and their Uses_. It will help to prevent mistakes like
this and more generally to make sharp and clear the fundamental
relations which exist between demand, supply and price, if we exhibit
them pictorially in the form of a diagram. Such diagrams are of great
service in many parts of economic theory, not because they can prove
anything which could not be proved otherwise, but because, being
really a simpler medium of expression than words, they enable the mind
to grasp more readily and to retain more vividly the essential facts
of complex relations.

Figure 1:

Y
|
| S'
| *
D | **
|* **
| ** *
| ** *
| * *
| ** **
| ** *
| ** *
| ** **
| ** *
| ** Q **