Note E268 — 45.
Reading edition
"Rew." Shakspere, Hamlet, iv. 5. 181: "There's rue for you; and here's some for me: we may call it herb-grace o' Sundays." And Winter's Tale, iv. 4. 74:
"For you there's rosemary and rue; these keep Seeming and savour all the winter long: Grace and remembrance be to you both."
Some suppose it to have been called "herb of grace" on account of the many excellent properties it was held to possess, being a specific against poison, the bites of venomous creatures, etc.; but probably it was so called because "rue" means "repent." Cf. also Richard II. Act iii. sc. 4. 105:
"Here in this place I'll set a bank of rue, sour herb of grace."