“The production of wealth by private enterprise is called Capitalism. It is hard to call Capitalism one of the isms, because Capitalism is not a creed at all. Capitalism was not ‘invented’ by any sociologist or philosopher. Capitalists never called themselves that. The word was invented by socialists to describe what they hated.”

Source: A Treatise On Political Economy (Fourth Edition) (1832), Book I, On Production, Chapter III, p. 73

1910s, The Progressives, Past and Present (1910)
Context: To my mind the failure resolutely to follow progressive policies is the negation of democracy as well of progress, and spells disaster. But for this very reason I feel concern when progressives act with heedless violence, or go so far and so fast as to invite reaction. The experience of John Brown illustrates the evil of the revolutionary short-cut to ultimate good ends. The liberty of the slave was desirable, but it was not to be brought about by a slave insurrection. The better distribution of property is desirable, but it is not to be brought about by the anarchic form of Socialism which would destroy all private capital and tend to destroy all private wealth. It represents not progress, but retrogression, to propose to destroy capital because the power of unrestrained capital is abused. John Brown rendered a great service to the cause of liberty in the earlier Kansas days; but his notion that the evils of slavery could be cured by a slave insurrection was a delusion analogous to the delusions of those who expect to cure the evils of plutocracy by arousing the baser passions of workingmen against the rich in an endeavor at violent industrial revolution. And, on the other hand, the brutal and shortsighted greed of those who profit by what is wrong in the present system, and the attitude of those who oppose all effort to do away with this wrong, serve in their turn as incitements to such revolution; just as the insolence of the ultra pro-slavery men finally precipitated the violent destruction of slavery.

Anarchism: Its Philosophy and Ideal (1896)
Context: What economists call over-production is but a production that is above the purchasing power of the worker, who is reduced to poverty by Capital and State. Now, this sort of over-production remains fatally characteristic of the present capitalist production, because — Proudhon has already shown it — workers cannot buy with their salaries what they have produced and at the same time copiously nourish the swarm of idlers who live upon their work.
The very essence of the present economic system is, that the worker can never enjoy the well-being he has produced, and that the number of those who live at his expense will always augment. The more a country is advanced in industry, the more this number grows. Inevitably, industry is directed, and will have to be directed, not towards what is needed to satisfy the needs of all, but towards that which, at a given moment, brings in the greatest temporary profit to a few. Of necessity, the abundance of some will be based on the poverty of others, and the straitened circumstances of the greater number will have to be maintained at all costs, that there may be hands to sell themselves for a part only of that which they are capable of producing; without which, private accumulation of capital is impossible!
These characteristics of our economical system are its very essence. Without them, it cannot exist; for, who would sell his labor power for less than it is capable of bringing in, if he were not forced thereto by the threat of hunger?
And those essential traits of the system are also its most crushing condemnation.

Interview with Parker in Randall E. Parker(ed.), Reflection on the Great Depression (2002)

Statement (8 June 1990), as quoted in The Economics of the Environment and Natural Resources (2004) by R. Quentin Grafton, p. 277
As quoted in The Guardian [London] (21 June 1990)
1990s
Variant: The market came with the dawn of civilization and it is not an invention of capitalism. … If it leads to improving the well-being of the people there is no contradiction with socialism.

Source: (1776), Book II, Chapter I, p. 305.

Source: Imperialism, The Highest Stage of Capitalism (1917), Chapter Three

at least as a deliberate method of economic organization.... The flipside of this bounty, this endless feast, is scarcity.
All You Can Eat: Greed, Lust and the New Capitalism (2001)

Source: Money: Whence It Came, Where It Went (1975), Chapter XXI, Afterword, p. 312