IN the Long March toward the New Deal and a planned economy, Leo Nebbia became an early, celebrated casualty. The state of New York, in advance of the New Deal, had fixed the price of milk at nine cents a quart as part of a scheme of social uplift. What would be lifted, or kept aloft, would be the income of the producers. The superstition, widely shared at the time, was that the economy would be kept buoyant in this way, by preserving the purchasing power of the producers and vendors. Nebbia ran afoul of this scheme through a modest act tinged with calculation: He would give a loaf of bread free to any customer who would buy two quarts of milk for 18 cents.  For that minor flexing of imagination, or for that retrograde motive of seeking a bit more business for himself by offering more value for the money, Nebbia could be stamped a “criminal.”