We understand early on that employing the Ring is too hazardous to contemplate, and will simply lead to a different kind of doom, at best. Sauron is worried th

We understand early on that employing the Ring is too hazardous to contemplate, and will simply lead to a different kind of doom, at best. Sauron is worried that Saruman or Gandalf or Galadriel or Elrond or Aragorn could successfully command the full powers of the Ring, gather together the might of Men, and beat him down to nothingness, so that he must suffer another 3000 years of powerlessness before trying again. Sauron may suspect that another could not do as much. But how could he know with certainty? He only has fifth hand reports of Isildur's tenure as the bearer of the Ring. The Ring was intended as a powerful tool for Sauron himself -- its nature in the hands of others may be as much a mystery to Sauron as anyone else.