Out of sight, out of mind
Dai Vernon popularized and significantly contributed to Out of Sight Out of Mind, but was not its sole creator in the sense of inventing the very first iteration of the effect. However many people still think so. It can be traced back to manuscripts from the 1600s. Find some variations below ending with a detailed explanation of the classic routine, which will help to understand variations. Bonus: learn Grasshopper as performed by Michael