above their value, in which case capitalists could raise prices at whim, but that commodities sold at or near their natural value produce profit because workers are only paid for that portion of their work which pays for their own labour power, i.e. that labour which generates enough value to pay workers their wages. In this regard Marx distinguishes value as the natural price of a commodity through the labour power invested in it, which forms an upper limit to wages, and the rate of profit as the ratio between the surplus value left to the capitalist after paying the wage, and the wage itself, thus excluding investments in capital prior to production, and disregarding payments by capitalists in rent to landlords and interest to moneylenders which must come from surplus value after production. This ratio, the difference between the value created by the "last employed worker" and the wage paid to that worker, which constitutes Marx's use of the word "exploitation." Marx concludes that as value is determined by labour, and as profit is the appropriated surplus value remaining after paying wages, that the maximum profit is set by the minimum wage necessary to sustain labour, but is in turn adjusted by the overall productive powers of labour using given tools and machines, the length of the workday, the intensity of work demanded, and the fluctuating prices of commodities such as metals and foodstuffs which determine how much a worker may purchase with wages expressed in money. All of these factors being a product of a given social arrangement, in this case the system of wage labour itself, the worker is left at the mercy of commodities and the cycles of capitalism, but not at the whim of the capitalists who pay their wages, who will lower wages during a decrease in the value of labour, but will resist efforts to increase wages during the cyclical upswings and despite any other factors which might increase the value of labour back to its average, natural level. Thus insisting that workers can not only exert pressure to increase their wages as a reflection of the value of their labour as a commodity, but must in fact organize to do so lest the inherent pressures of capitalism reduce them to "one level mass of broken wretches past salvation," Marx nonetheless declares unionism to be a conservative force so long as it restricts