E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
The sympathetic powder, supposed to possess a healing influence from a distance. The mediæval philosophers were very fond of calling books, drugs, etc., connected with alchemy and astrology by the term hermetic, out of compliment to Herms Trismegistus. (Sir Kenelm Digby: Discourse Concerning the Cure of Wounds by Sympathy.)