It will help us to get rid of the difficulty presented by petty industry and agriculture if we bear in mind that collective ownership is not, as is commonly supposed, the supreme, fundamental condition of Socialism. It is proposed only as a means to an end, not as the end itself. The wealth producers are exploited by a class whose source of income is the surplus-value extracted from the workers. Instinctively, the workers struggle against that exploitation, to reduce the amount of surplus-value taken by the capitalists to a minimum. To do away with that exploitation social ownership and control is proposed. If the end could be attained more speedily by other methods, those methods would be adopted. It follows, therefore, that to make collective property of things not used as a means of exploiting labor does not necessarily form part of the Socialist programme. True, some such things might be socialized in response to an urgent demand for efficiency, but, of necessity, the struggle will be principally concerned with the socializing of the means of production which are used as means of exploitation by a class deriving its income from the surplus-value produced by another class. It is easy enough to see that, according to this principle of differentiation, it would be necessary to socialize the railroad, but not at all necessary to socialize the wheelbarrow; while it would be necessary to socialize a clothing factory, it would not be necessary to take away a woman's domestic sewing machine. Independent, self-employment, as in the case of a craftsman working in his own shop with his own tools, or groups of workers working cooeperatively, is quite consistent with Socialism. In the Socialist state, then, certain forms of private industry will be tolerated, and perhaps even definitely encouraged by the state, but the great fundamental economic activities will be collectively managed. The Socialist state will not be static and, consequently, what at first may be regarded as being properly the subject of private enterprise may develop to an extent or in directions which necessitate its transformation to the category of essentially social properties. Hence, it is not possible to give a list of things which would be socialized and another list of things which would remain private property, but perfectly possible to state the principle which must be the chief determinant of the extent of socialization. With this principle in mind it is fairly possible to sketch the outlines at least of the economic development of the collectivist commonwealth; the conditions essential to that stage of social evolution at which it will be possible and natural to speak of capitalism as a past and outgrown stage, and of the present as the era of Socialism.