“We speak of a manly man, but not of a whaley whale. If you wanted to dissuade a man from drinking his tenth whisky, you would slap him on the back and say, ‘Be a man.’ No one who wished to dissuade a crocodile from eating his tenth explorer would slap it on the back and say, ‘Be a crocodile.'”

— G.K. Chesterton, The Religious Doubts of Democracy, 1903

The Real World

I had a growing feeling in the later years of my work at the subject that a good mathematical theorem dealing with economic hypotheses was very unlikely to be good economics: and I went more and more on the rules — (1) Use mathematics as a shorthand language, rather than an engine of inquiry. (2) Keep to them until you have done. (3) Translate into English. (4) Then illustrate by examples that are important in real life. (5) Burn the mathematics. (6) If you can’t succeed in 4, burn 3. This last I did often.

— Alfred Marshall, in a letter to A.L. Bowley, Jan. 27, 1906