How we cite our quotes: (Chapter.Section.Paragraph) or (Chapter.Paragraph)
Quote #1
When we leave this sphere of simple circulation or the exchange of commodities, which provides the 'free-trader vulgaris' with his views, his concepts and the standard by which he judges the society of capital and wage-labour, a certain change takes place, or so it appears, in the physiognomy of our dramatis personae. He who was previously the money-owner now strides out in front as a capitalist; the possessor of labour-power follows as his worker. The one smirks self-importantly and is intent on business; the other is timid and holds back, like someone who has brought his own hide to market and now has nothing else to expect but—a tanning. (6.23)
Most of the time in Das Kapital, Marx thinks of the capitalist and the worker as impersonal forces: capital and labor-power. But here he lets go a bit and describes them as people. In contrast to the views of pop economists who promoted capitalism—the free-trader vulgaris—Marx sees the relationship as one of power, where the capitalist dominates the worker and is able to tan him (abuse him). That's because the capitalist owns the means of production, whereas the worker can only sell his labor-power.
Quote #2
The fact that half a day's labour is necessary to keep the worker alive during 24 hours does not in any way prevent him from working a whole day. Therefore the value of labour-power, and the value which that labour-power valorizes in the labour-process, are two entirely different magnitudes; and this difference was what the capitalist had in mind when he was purchasing the labour-power [...] What was really decisive for him was the specific use-value which this commodity possesses of being a source not only of value, but of more value than it has itself. (7.2.22)
With the means of production owned, the capitalist is in the powerful position of being able to hire a commodity that can produce value. Meanwhile, the worker is that lowly producer, overpowered. Marx saw this relationship and advocated the overthrow of capitalism in the Communist Manifesto.
Quote #3
The capitalist maintains his rights as a purchaser when he tries to make the working day as long as possible, and, where possible, to make two working days out of one. On the other hand, the peculiar nature of the commodity sold implies a limit to its consumption by the purchaser, and the worker maintains his right as a seller when he wishes to reduce the working day to a particular normal length. There is here therefore an antinomy, of right against right, both equally bearing the seal of the law of exchange. Between equal rights, force decides. Hence, in the history of capitalist production, the establishment of a norm for the working day presents itself a a struggle over the limits of that day, a struggle between collective capital, i.e. the class of capitalists, and collective labour, i.e. the working class. (10.1.8)
In the perfectly functioning, ideal capitalism Marx describes, the contract between the capitalist and the worker is a one in which each party is on equal legal footing. So their rights, being equal, don't decide who gets to call the shots over the length of the working day. What decides is force—that is, power. The stronger party gets to determine the length of the working day. Capitalists are stronger in that they own the means of production, but workers are stronger in that they are greater in number.
Quote #4
These 'small thefts' of capital from the workers' meal-times and recreation times are also described by the factory inspectors as 'petty pilferings of minutes', 'snatching a few minutes' or, in the technical language of the workers, 'nibbling and cribbling at meal-times'. (10.2.14)
When capitalists overpower workers, the bosses are able to unfairly take promised mealtimes away from their employees. Necessary components of human existence—eating, resting—are at risk when a powerful class gets to call the shots over them.
Quote #5
Hence it is self-evident that the worker is nothing other than labour-power for the duration of his whole life, and that therefore all his disposable time is by nature and by right labour-time, to be devoted to the self-valorization of capital. Time for education, for intellectual development, for the fulfillment of social functions, for social intercourse, for the free play of the vital forces of his body and his mind, even the rest time of Sunday (and that in a country of Sabbatarians!)—what foolishness! (10.5.1)
In 19th-century Europe, powerful capitalists, bent on squeezing as much productivity out of workers as possible, didn't want to allow time for education, social functions, rest, or the other things listed by Marx in this passage.
Quote #6
But in its blind and measureless drive, its insatiable appetite for surplus labour, capital oversteps not only the moral but even the merely physical limits of the working day. It usurps the time for growth, development and healthy maintenance of the body. It steals the time required for the consumption of fresh air and sunlight. It haggles over the meal-times, where possible incorporating them into the production process itself [...] It reduces the sound sleep needed for the restoration, renewal and refreshment of the vital forces to the exact amount of torpor essential to the revival of an absolutely exhausted organism. (10.5.1)
This is another depiction of the exploitation of workers by the powerful capitalists. They go so far as to take time away that's needed for health. In Chapter 10, Marx describes how the owners wanted the factories to run 24 hours a day, and how they'd keep workers from getting enough sleep.
Quote #7
Capital asks no questions about the length of life of labour-power. What interests it is purely and simply the maximum of labour-power that can be set in motion in a working day. It attains this objective by shortening the life of labour-power, in the same way as a greedy farmer snatches more produce from the soil by robbing it of its fertility. (10.5.1)
Marx says the capitalists in 19th-century Europe used their power so unjustly as to not care if their quest for profit shortened workers' lives. Brutal working conditions still exist today, as in the maquiladoras in Mexico or child mines in Africa.
Quote #8
By extending the working day, therefore, capitalist production, which is essentially the production of surplus-value, the absorption of surplus labour, not only produces a deterioration of human labour-power by robbing it of its normal moral and physical conditions of development and activity, but also produces the premature exhaustion and death of this labour-power itself. It extends the worker's production-time within a given period by shortening his life. (10.5.2)
Surplus labor has been absorbed or taken from the have-nots by the haves throughout history under many different modes of production, not just capitalism. Marx sees class struggle as the best lens through which to view history (take a look at the Communist Manifesto), so he might argue that the seizure of surplus labor is the most basic way in which unjust power is exercised.
Quote #9
Capital therefore takes no account of the health and the length of life of the worker, unless society forces it to do so. Its answer to the outcry about the physical and mental degradation, the premature death, the torture of over-work, is this: Should that pain trouble us, since it increases our pleasure (profit)? But looking at these things as a whole, it is evident that this does not depend on the will, either good or bad, of the individual capitalist. Under free competition, the immanent laws of capitalist production confront the individual capitalist as a coercive force external to him. (10.5.8)
The horrible examples of exploitation in Chapter 10 notwithstanding, Marx emphasizes that he's most of all talking about unjust power being an impersonal force of capital, not something dependent on whether individual capitalists are good or bad people. What do you think? Is the exercise of unjust power to be blamed on systemic forces or on individual people?
Quote #10
For 'protection' against the serpent of their agonies, the workers have to put their heads together and, as a class, compel the passing of a law, an all-powerful social barrier by which they can be prevented from selling themselves and their families into slavery and death by voluntary contract with capital. (10.7.7)
The working class isn't powerless. Workers can take advantage of their size—they outnumber the large capitalists by the millions—by joining together and striking or putting pressure on the government to pass laws for the regulation of working conditions and the length of the working day. Of course, Marx would have them do more than that as well—he'd tell them to revolt and overthrow capitalism altogether.