Some many argue that it is foolish to set the railroads off against aluminum or the movies off against glass. Are not aluminum and glass naturally so versatile that the industries are bound to have more growth opportunities than the railroads and the movies? This view commits precisely the error I have been talking about. It defines an industry or a product or a cluster of know-how so narrowly as to guarantee its premature senescence. When we mention "railroads" we should make sure mean "transportation" As transporters, the railroads still have a good chance for very considerable growth. They are not limited to the railroad business as such (though in my opinion, rail transportation is potentially a much stronger transportation medium than is generally believed).