John Nevil Maskelyne,
Sharps and Flats
“ Probably it was at no very recent date in the history of card-playing that some genius first recognised the advantage which would accrue to a player who could devise some means of placing a distinctive mark on the back of each card, imperceptible to all but himself, to indicate its suit and value. Every card-player must at some time or other have exclaimed mentally, 'Oh, if I only knew what cards my opponents hold!' There one has, then, the origin of marked cards. The sharp, above all others, desires to know his opponent's cards. ”
