• The marginal revolution: value from marginal utility, not labour (ECO-I 2.5's bridge); analysis at the margin (the optimizing agent);
• Marshall's partial equilibrium: supply and demand's scissors, ceteris paribus (ECO-I Unit 2's apparatus); Walras's general equilibrium (all markets interlinked); efficiency and welfare theorems' foundation (Unit 6.3's economics);
• Policy: markets efficient; the state corrects at the edges; the self-correcting economy (price flexibility) — unemployment temporary.