Great synthesizer of neoclassical economics, teacher of Keynes
An English economist, the great synthesizer of neoclassical economics and founder of modern microeconomics. He brought together the two threads of the classical school’s "cost of production" and the marginal revolution’s "subjective utility," resolving the dispute with a famous metaphor: what determines price is the two blades of the "scissors" of supply and demand, neither dispensable. His Principles of Economics introduced supply and demand curves, elasticity, marginal analysis — a whole toolkit — and became the standard textbook for generations. Teaching at Cambridge, he trained a group of economists including Keynes — many of the basic concepts of modern economics come from his ordering.
The classical school said value is set by cost of production, the marginalists said by subjective utility, and the two could not agree. Marshall reconciled them with an apt metaphor: to ask "does supply or demand set price" is like asking "does the upper or lower blade of the scissors cut the paper" — the answer is both blades together. This framework of supply and demand jointly setting price still opens every economics textbook.
Below are how modern works borrow or reinterpret this name or story — not the original material. The two differ, so keep them apart.