A day like today, exactly 25 years ago, my admired advisor Sherwin Rosen died, way too young, at 62 years of age. He was then the president of the AEA. We owe him some crucial ideas. I highlight 7. Hedonic Prices and Implicit Markets (JPE, 1974). How does the market price something as complex as a car, a house, or a job? Goods are bundles of characteristics. In equilibrium, the price schedule is the envelope of heterogeneous buyers' bids and heterogeneous sellers' offers—so market prices reveal the implicit value of each characteristic. Key to environmental valuation, the value of life, and urban quality-of-life indexes. Monopoly and Product Quality (JET, 1978, with Mussa). Did you wonder if your tourist class seat is too narrow? A monopolist who faces buyers differing in taste for quality degrades what she sells to low types so high types can't mimic them and capture the surplus. The foundational screening model. Education and Self-Selection (JPE, 1979, with Willis). Do grads from better colleges earn more because of how much they know? People sort into college by comparative advantage: those who go are better at college-type work, those who don't are better at non-college work. The returns need to be corrected. A crucial idea for an entire literature. The Economics of Superstars (AER, 1981). Why do rewards concentrate at the top in music, movies, sports etc.? When output can be replicated at zero marginal cost, and there is little substitutability in production, small talent differences produce enormous earnings gaps. The economics of the internet, twenty years early. Rank-Order Tournaments (JPE, 1981, with Lazear). When individual output is noisy, firms pay on rank; the spread between winner and loser is the instrument that elicits effort. Authority, Control, and the Distribution of Earnings (Bell Journal, 1982). In a hierarchy, each manager's talent is multiplied across everyone below her. A slightly better person at the top is worth disproportionately more- a better general decides which war we fight, hence affects all of our marginal products. That is why we see convexity of pay at the top of organizations. Prizes in Elimination Tournaments (AER, 1986). In a multi-round promotion ladder, the biggest jump must come in the final round, because the option value of future rounds has vanished, only the current prize can motivate. Professor Rosen would look distracted in seminars. He would look confused. Then he'd say something that changed the entire analysis and discussion. He never tried to look good at the speaker's expense. He just saw the problem more deeply than anyone in the room- no exceptions. One personal anecdote: during my PhD studies, I was totally depressed: I could not advance, all my ideas were awful. I could not bear going to his office. As i was coming upstairs towards the 4th floor of the Social Science building I met him in the stairs. He said. "I have not seen you, Luis, for a while." I said "Sorry Prof. Rosen, I had nothing to show you." He said "Well, you have to come. Come every week, whether you have something or not". incredibly, that short exchange was probably the most important one in my life. The duty to go to his room got me out of the hole.