Every time you play a hand differently from the way you would have played it
if you could see all your opponents' cards, they gain; and every time you play
your hand the same way you would have played it if you could see all their cards,
they lose. Conversely, every time opponents play their hands differently from
the way they would have if they could see all your cards, you gain; andevery
time they play their hands the same way they would have played if theycould see
all your cards, you lose.
Fundamental theorem of poker : David Sklansky