“But wait, I can save you, free you from the great danger. Look, here is a potent drug. Take it to Circe's halls – its power alone will shield you from the fatal day. Let me tell you of all the witch's subtle craft... She'll mix you a potion, lace the brew with drugs but she'll be powerless to bewitch you, even so – this magic herb I give will fight her spells.” What is the meaning of the word potent as it is used above?