In the case of competitive profits which we have just been discussing the far-seeing enterpriser was able to reap competitive profits from price fluctuations, although he was not able to regulate price because of the competition of other enterprisers. Where an enterpriser is free, or comparatively free, from the competition of other enterprisers and is able to control the supply of a commodity, he can, by limiting the supply, raise prices to a certain extent. When prices are raised in this way, the resulting increased margin between selling prices and the costs of production give rise to monopoly profits. As we have already learned, there is a limit beyond which the monopolists will not go in increasing prices for the reason that a further increase in prices would result in a lessening of total profits. Often, too, the enterpriser who is a monopolist is afraid that if he raises the price too high, a competitor will enter the field to contest his monopoly and attempt to secure some of the excessive profits. Moreover, as we have learned in an earlier chapter, where the monopolist attempts to secure too high profits, consumers are likely in many cases to substitute other goods and thus to defeat the monopolist's purpose.