The increment of the commodity which he is only just induced to acquire (whether by... direct labor or by purchase) may be called its Marginal Increm… - Alfred Marshall

I am myself an uncompromising anti-Jingoe, a peace-at-almost-any-price man. Chamberlain is the only Unionist public man whom I have ever thoroughly distrusted. Excepting Napoleon, I believe that England's true greatness has had no such dangerous enemy since Lord North. When a radical, he delighted to dish his colleagues even more than to flout his opponents. He is now engaged in dishing his new colleagues and flouting his old friends.

I have not been able to lay my hands on any notes as to Mathematico-economics that would be of any use to you. I have very indistinct memories of what I used to think on the subject. I never read mathematics now: in fact I have even forgotten how to integrate a good many things.
But I know 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 well unlikely to be good economics: and I went more and more on the rules—(1) Use mathematics as a shorthand language, rather than as an engine of inquiry. (2) Keep to them till 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 do often.

Political Economy or Economics is a study of mankind in the ordinary business of life; it examines that part of individual and social action which is most closely connected with the attainment and with the use of the material requisites of wellbeing.