There is, of course, no difference in _area_ between a mile square and a square mile. But there may be considerable difference in _shape_. A mile square can be no other shape than square; the expression describes a surface of a certain specific size and shape. A square mile may be of any shape; the expression names a unit of area, but does not prescribe any particular shape.
124.--A QUESTION OF DEFINITION.
From Amusements in Mathematics by Henry Ernest Dudeney.
