Jean P. H. E. A. Esmein and Walter A. Phillips, 1911 Encyclopædia Britannica (1911)
“ But in the second half of the 14th century certain royal taxes levied throughout the whole of the domain of the Crown, tended to become permanent, and independent of the vote of the estates. This sprang from many causes, but from one in particular; the Crown endeavoured by transforming and changing the nature of the "feudal aid" to levy a general tax by right, on its own authority, in such cases as those in which a lord could demand feudal aid from his vassals. ”
