I am convinced that the ability to "memorize" scores and conduct without
them is a very special talent which indeed does involve perfect audio and
visual memories and which very few indidividuals possess.  Mitropoulos and
Toscanini have been mentioned as examples, and from what I observed, the
Minneapolis SO seemed very comfortable with this arrangement.  I never had
the good fortune to see Toscanini conduct live, but the Toscanini mythos
represents him as being aware of, and habitually pointing out to the
offenders, any missed, omitted, or misplayed notes in a piece.  Although
I never have aspired to conducting, my experience has been that those
conductors who do not possess that special talent should accept their
fates and not give hostages to fortune.

Paul