Marx’s Economic Manuscripts of 1861-63
2) Absolute Surplus Value by Karl Marx
Capital has in common with hoarding the boundless tendency to self-enrichment. Because surplus value is reducible to surplus labour, capital has a boundless drive to increase surplus labour. Capital endeavours, in return for the objectified labour expended in wages, to obtain the greatest possible quantity of living labour time, i.e. the greatest possible excess of labour time over and above the labour time required for the reproduction of the wage, i.e. the reproduction of the value of the daily means of subsistence of the worker himself. The whole of capital’s history is a proof of its unrestrained extravagances in this respect. The tendency is evident everywhere without concealment, and it is only held in check in part by physical conditions, and in part by social obstacles, which we shall not go into in any more detail here (and which that tendency itself is the first to create). All we need do here is note the tendency. In this respect it is interesting for example to compare the modern factory system in England with corvée labour, perhaps in the Danubian Principalities. The two forms, of which one is a developed capitalist form and the other is among the crudest forms of serfdom, display with equal clarity the appropriation of alien excess labour, of surplus labour, as the direct source of enrichment. The special circumstances additionally present in the factory system, in the developed capitalist mode of production, which allow labour time to be lengthened unnaturally, beyond its natural bounds, can only be indicated more closely in the course of this investigation.
In comparing Walachian corvée labour with English wage labour the following point is to be kept in view. If the total daily labour time of a worker consists of 12 or 14 hours, and the necessary labour time in each case amounts to only 10 hours, the worker would provide in the course of 6 days of the week in the first case 6 × 2 or 12 hours of surplus labour, in the second case 6 × 4 or 24 hours of surplus labour. In the first case [he] would work one day out of 6 for the capitalist without equivalent, in the second case 2 days. Over the whole year, week in week out, the situation can be resolved into this: he works 1, 2 or x days a week for the capitalist, but the other days of the week he works for himself. This is the form in which the relation appears directly in corvée labour, that of Walachia for example. In essence the general relation is in both cases the same, although the form — the mediation of the relation — is different.
There are, however, natural barriers to the duration of the daily labour time of a particular individual. Leaving aside the time required for the intake of food, the individual needs sleep, relaxation, needs a break during which labour capacity and its organ can enjoy the rest without which they are incapable of continuing the work or starting afresh. The day itself can be characterised as the natural measure of labour’s duration, and indeed in England the 12 hour day is called the “Working Day”. The limits of the working day are however indistinct, and we find it extended from 10 to 17 (18) hours among different nations and in specific branches of industry within the same nation. The periods of work and rest can be displaced, so that for example work can be done during the night, with the daytime for resting, sleeping. Or the working day can be distributed between day and night. In the Russian factories in Moscow, for example, we find that work proceeds for 24 hours, day and night. (This was also the case in large part in the early days of the English cotton industry.) But then two teams (sets) of workers are employed. The first team works 6 hours during the day and is then replaced by the second team. After that the first team again works for 6 hours during the night and is then again replaced for the following 6 hours by the second team. Or (as in the case of the dressmaker, which is to be cited) (bakers too) 30 hours can be worked, one after another, and then a break, etc. 
[III-100] The examples (to be brought in here) on the extraction of labour time are also useful, because they show strikingly how value, i. e. wealth as such, can simply be reduced to labour time.
We have seen that the capitalist pays labour capacity its equivalent, and that the valorisation of labour capacity beyond its value does not stand in contradiction to this operation, which occurs according to the law of the exchange of commodities namely the law that commodities exchange in proportion to the labour time contained in them, or in proportion to the labour time required to produce them — on the contrary, that it proceeds from the specific nature of the use value of the commodity which is being sold here. Hence the degree to which labour capacity is valorised by the capitalist, or the extent to which the duration of labour time in the actual production process is increased, appears to be a matter of complete indifference, i. e. it does not appear to be given by the nature of the relation itself. That is to say, in other words: The magnitude of the living surplus labour, hence also of the total living labour time obtained by capital in exchange for a particular quantity of objectified labour, determined by the cost of production of labour capacity itself, appears to be subject to just as little restriction by the nature of this economic relation itself as the manner in which a buyer utilises the use value of a commodity is determined by the relation of sale and purchase as such. It is much rather independent of this. The limits that develop here — e. g., later, economically from the relation of supply and demand or from state intervention and the like — do not, by contrast, appear to be included in the general relation itself.
Nevertheless , the following point must be considered: What on capital’s side is the valorisation of labour capacity (or, as we previously called it, the consumption of labour capacity — it is of the nature of labour capacity that its consumption is at the same time a process of valorisation, objectification of labour) is on the worker’s side work, hence the expenditure of vital force. If labour is prolonged beyond a certain period — or labour capacity is valorised to more than a certain extent — labour capacity will be temporarily or definitively destroyed, instead of being preserved. If the capitalist sets the worker to work for e. g. 20 hours today, tomorrow he will be incapable of working the normal labour time of 12 hours or perhaps any labour time at all. If the overwork extends over a long period, the worker will perhaps only preserve himself and therefore his labour capacity for 7 years instead of the 20 or 30 years for which he might otherwise have preserved it. It is well known, for example, that before the invention of the cotton gin the 2 hours of manufacturing labour (domestic labour) the slaves in the southern states of North America had to perform to separate the cotton wool from its seed, after they had worked in the fields for 12 hours, reduced their average life expectancy to 7 years. This is still at this moment the case in Cuba, where after 12 hours in the fields the Negroes have a further two hours of manufacturing labour to perform in connection with the preparation of sugar or tobacco.
But if the worker sells his labour capacity at its value — and we are proceeding from this assumption in our investigation, just as we proceed altogether from the presupposition that commodities are sold at their value a — all that is assumed thereby is that he receives an average daily wage which enables him to continue living in his customary manner as a worker, hence that he is in the same normal state of health the day afterwards as the day before (leaving aside the degeneration brought about naturally through age or through the kind of work he does); that his labour capacity is reproduced or preserved, hence can be valorised again in the same way as on the previous day, over a definite normal period of time, e. g. 20 years. Thus if surplus labour is stretched out to an extent of overwork which forcibly shortens, temporarily annihilates, i. e. damages or entirely destroys, the normal duration of labour capacity this condition is breached. The worker places the use of his labour capacity at [the capitalist’s] disposal — if he sells it at its value — but only to such an extent as to rule out the destruction of the value of the labour capacity itself, or rather, only to an extent sufficient to ensure that the wage enables him to reproduce his labour capacity, to preserve it throughout a certain normal average time. If the capitalist uses the worker for longer than this normal labour time, he destroys the labour capacity and with that its value. He has, after all, only bought the labour capacity’s average daily [III-101] value, hence by no means the value it possesses on the next day as well. In other words, he has not bought in 7 years the value it possesses during 20.
Hence, as, on the one hand, the specific use value of this commodity — labour capacity — implies that its consumption is itself valorisation, the creation of value, so on the other hand, the specific nature of this use value implies that the extent to which it can be consumed, valorised, must be kept within certain limits to prevent the destruction of its own exchange value.
Here, where we are making the overall assumption that the worker sells his labour capacity at its value, we also assume that the total period, the sum of the necessary labour time and the surplus labour time, does not exceed the normal working day, whether this is set at 12, 13 or 14 hours, worked by the worker in order to preserve his labour capacity in its customary state of health and ability to work for a certain normal average period, and to reproduce it every day afresh.
It follows from what has been said, however, that there is an antinomy here in the general relation itself. This antinomy arises in the following way: On the one hand, if we disregard the natural limit which absolutely prohibits the extension of labour time beyond a certain duration, the general relation between capital and labour — the sale of labour capacity — posits no limit to surplus labour. But on the other hand, in so far as surplus labour destroys the value of labour capacity itself, whereas labour capacity’s use is only sold to the extent to which it preserves and reproduces itself as labour capacity, implying also the preservation of its value throughout a definite normal period of time, surplus labour which goes beyond a certain indeterminate boundary contradicts the very nature of the relation which is given with the worker’s sale of his labour capacity.
We know that in practice it depends on the relative power of the buyer and the seller (which is determined each time economically) whether a commodity is sold at less or more than its value. Similarly here. Whether the worker provides surplus labour of more than the normal amount or not will depend on the power of resistance he is able to oppose to the measureless demands of capital. The history of modern industry teaches us, however, that the measureless demands of capital could never be held in check by the isolated efforts of the worker. The struggle had instead to take on the form of a class struggle, and thereby call forth the intervention of the state power, before the overall daily labour time was confined within certain limits (as yet mostly within certain spheres alone).
One might think that, just as the slave-owner, when he has consumed the Negro in 7 years, is compelled to replace him with a fresh purchase of Negroes, so capital must itself pay for the rapid exhaustion of the workers, since the continuous existence of the working class is capital’s fundamental prerequisite. The individual Capitalist A may have enriched himself through this “killing no murder”,  whereas Capitalist B has perhaps to pay the expenses, Or Generation B of the capitalists does. Nevertheless, the individual capitalist perpetually rebels against the overall interest of the capitalist class. On the other hand, the history of modern industry has shown that continuous overpopulation is possible, although it consists of a stream of human generations plucked so to speak before they are ripe, quickly wasted and following each other in rapid succession. (See the passage in Wakefield)