In all the talk in the Principles (as opposed to the formal analysis) it is not the saving of rentiers but the energy of entrepreneurs which governs accumulation.

Progress is slow partly from mere intellectual inertia. In a subject where there is no agreed procedure for knocking out errors, doctrines have a long life. A professor teaches what he was taught, and his pupils, with a proper respect and reverence for teachers, set up a resistance against his critics for no other reason than that it was he whose pupils they were.

It's a terrible thing to be a worker exploited in the capitalist system. The only worse thing is to be a worker unable to find anyone to exploit you.

It is a popular error that bureaucracy is less flexible than private enterprise. It may be so in detail, but when large scale adaptations have to be made, central control is far more flexible. It may take two months to get an answer to a letter from a government department, but it takes twenty years for an industry under private enterprise to readjust itself to a fall in demand.

science progresses by trial and error, and when it is forbidden to admit error there can be no progress.

The very nature of economics is rooted in nationalism. ... It [was] developed ... in the hope of throwing light upon questions of policy. But policy means nothing unless there is an authority to carry it out, and authorities are national.

Reality is never a golden age.