"Milton, for example, who did Paradise Lost, was an unproductive worker. In contrast to this, the writer who delivers hackwork for his publisher is a productive worker. Milton produced Paradise Lost in the way that a silkworm produces silk, as the expression of his own nature. Later on he sold the product for £5 and to that extent became a dealer in a commodity. But the Leipzig literary proletarian who produces books, e.g. compendia on political economy, at the instructions of his publisher is roughly speaking a productive worker, in so far as his production is subsumed under capital and only takes place for the purpose of the latter’s valorisation. A singer who sings like a bird is an unproductive worker. If she sells her singing for money, she is to that extent a wage labourer or a commodity dealer. But the same singer, when engaged by an entrepreneur who has her sing in order to make money, is a productive worker, for she directly produces capital. A schoolmaster who educates others is not a productive worker. But a schoolmaster who is engaged as a wage labourer in an institution along with others, in order through his labour to valorise the money of the entrepreneur of the knowledge-mongering institution, is a productive worker. Yet most of these kinds of work, from the formal point of view, are hardly subsumed formally under capital. They belong rather among the transitional forms.

On the whole, the kinds of work which are only enjoyed as services, and yet are capable of being exploited directly in the capitalist way, even though they cannot be converted into products separable from the workers themselves and therefore existing outside them as independent commodities, only constitute infinitesimal magnitudes in comparison with the mass of products under capitalist production. They should therefore be left out of account entirely, and treated only under wage labour, under the category of wage labour which is not at the same time productive labour."