Failure to note the play of a card is not lack of memory, but lack of heed.
Situations are kaleidoscopic and constant, and success may only be achieved by being perpetually alert to note them.
All time at Bridge should be devoted earnestly to what confronts a player, not to what is past.
It is better not to play at all, than to play without earnestness.
One careful game is worth any number of slipshod, careless efforts which are disconcerting to your partner, and the delight of your adversaries.