William Arthur Shaw, The History of Currency, 1252 to 1896
“ A single instance will serve to show their nature. In 1342 the mark of gold, which in a normal time just preceding was valued at 41 livres 13 sols, was proclaimed equal to 117 livres, and in 1360 the mark of silver, valued normally at 5 livres, rose to 102 livres. [5] It stands to reason that such abnormal movements must be neglected in any attempt to determine the course of such fluctuations in value of the metals, and the ratio of gold and silver, as arose naturally from the metallic and currency history of the time. ”
