Upvote:8
Including all three phases:
(1) Primitive labour rent: the serf owed his lord some number of days labour usually in the lord's fields. (2) Rent paid in kind: the serf owed his lord some of the serf's produce. This might be so much corn or meat each year. (3) Rent paid in cash plus a considerable amount of corvΓ©e: the serf had to obtain some cash from trading his produce as well as some enforced labour (corvΓ©e).
This is a fairly normal development over the centuries that the feudal system operated. Labour becomes payment in kind instead of labour, which in turn becomes cash as the amount of cash in use increases.
Samuel Russel is right that you should include full quotes, it helps to understand the commentators stance. The link is also important since it is not paywalled and can be easily read.