It flows back to its starting point. Hence, the reflux is independent of the process itself. Both are commodities, and of equal value. But, at the same time, they are qualitatively different use-values, and the process has social metabolism as its content. To exchange 100 pounds for 100 pounds, and in a roundabout way to boot, seems absurd.
More money is withdrawn from circulation than has been thrown into it.
Once the need for expansion of value is given, it sexists for M' as well as for M, and the movement of capital is boundless, because its goal is as much unattained at the end of the process as at the beginning. As the representative of this process, the owner of money becomes a capitalist. More than that, as original value, it is differentiated from itself as surplus-value. It becomes money in process, and as such, capital. BUt, industrial capital, too, is money which is converted into commodities, and by the latter's sale reconverted into more money.