An attempt is made, in what follows, to restate and briefly explain the two most important contradictions in the capitalist economy, viz., the law of the falling rate of profits and the crisis caused by the failure to realize surplus value. In a sense, the problem of the realization of surplus value is vital to Marx's theory of capitalist development, because the tendency of the rate of profits to fall is, as will be seen later, significantly shaped by the problem of realization of surplus value.