From a Time Magazine article in 1959:

Darvas places his buy orders for levels that he considers breakout points on the upside. At the same time, he places a stop-loss sell order just below his buy order, so that if the stock does not move straight up after he buys, he will be sold out and his loss cut. “I have no ego in the stock market,” he says. “If I make a mistake I admit it immediately and get out fast.” Darvas thinks his system is the height of conservatism. Says he: “If you could play roulette with the assurance that whenever you bet $100 you could get out for $98 if you lost your bet, wouldn’t you call that good odds?” If he has a big profit in a stock, he puts the stop-loss order just below the level at which a sliding stock should meet support. He bought Universal Controls at 18, sold it at 83 on the way down after it had hit 102. “I never bought a stock at the low or sold one at the high in my life,” says Darvas. “I am satisfied to be along for most of the ride.”