We have just seen that, apart from money-capital, circulating capital is only another name for commodity-capital. But to the extent that labour power circulates in the market,it is not capital, no form of commodity-capital. It is not capital at all; the labourer is not a capitalist, although he brings a commodity to market, namely his own skin.
What strikes one here above all is the crudely empirical conception of profit derived from the outlook of the ordinary capitalist, which wholly contradicts the better esoteric understanding of Adam Smith.
It goes without saying that the normal durability of fixed capital is calculated on the supposition that all the conditions under which it can perform its functions normally during that time are fulfilled, just as we assume, in placing a mans life at 30 years on the average,that he will wash himself.
So far as living instruments of labour are concerned, for instance horses, their reproduction is timed by nature itself. Their average lifetime as instruments of labour is determined by the laws of nature. As soon as this term has expired they must be replaced by new ones. A horse cannot be replaced piecemeal; it must be replaced by another horse.
A circuit performed by a capital and meant to be a periodical process, not an individual act, is called its turnover. The duration of this turnover is determined by the sum of its time of production and its time of circulation.
In a constantly revolving circle every point is simultaneously a point of departure and a point of return. If we interrupt the rotation, not every point of departure is a point of return.
