That Protestant work ethic

From the other book I currently have on the go:

What was new in modern society was that men came to be driven to work not so much by external pressure but by an internal compulsion, which made them work as only a very strict master could have made people do in other societies.

The inner compulsion was much more effective in harnessing all energies to work than any outer compulsion can ever be. Against external compulsion there is always a certain amount of rebelliousness which hampers the effectiveness of work or makes people unfit for any differentiated task requiring intelligence, initiative and responsibility. The compulsion to work by which man was tuned into his own slave driver did not hamper these qualities. Undoubtedly capitalism could not have been developed had not the greatest part of man’s energy been channelled in the direction of work. There is no other period in history in which free men have given their energy so completely for one purpose: work. The drive for relentless work was one of the fundamental productive forces, no less important for the development of our industrial system than steam and electricity.