Microeconomics,, 16th Canadian Edition

variable) on the vertical axis. This is “backward” to what is usually done in mathematics. The
rational explanation of what is now economists’ odd practice is buried in the history of economics
and dates back to Alfred Marshall’s Principles of Economics (1890) [6]. For better or worse,
Marshall’s scheme is now used by all economists, although mathematicians never fail to wonder at
this example of the odd ways of economists.