The Riddle of the Herbal Chamber
In the depths of an ancient library, Empiric, the learned plague doctor, discovers a hidden passage leading to two mysterious doors. Behind one door lies a long-lost chamber filled with rare medicinal herbs that Empiric seeks. The other door, however, leads to a maze of tunnels that will take him far away from his quest.
Above the doors, an inscription reads: "One door always tells the truth, and the other always lies." Each door is guarded by a sentinel, one who speaks only truth and the other only falsehoods.
Empiric knows he can ask only one question to one of the sentinels to find the chamber of herbs. After pondering for a moment, he asks his question. With the answer, he confidently chooses the correct door.
The Riddle:
What question did Empiric ask to find the right door?