What is "hermetic books"

Hermetic \Her*met"ic\, Hermetical \Her*met"ic*al\, a. [F. herm['e]tique. See Note under Hermes,

1. ] 1. Of, pertaining to, or taught by, Hermes Trismegistus; as, hermetic philosophy. Hence: Alchemical; chemic. ``Delusions of the hermetic art.''
   --Burke.

   The alchemists, as the people were called who tried to make gold, considered themselves followers of Hermes, and often called themselves Hermetic philosophers.
   --A. B. Buckley.

2. Of or pertaining to the system which explains the causes of diseases and the operations of medicine on the principles of the hermetic philosophy, and which made much use, as a remedy, of an alkali and an acid; as, hermetic medicine.

3. Made perfectly close or air-tight by fusion, so that no gas or spirit can enter or escape; as, an hermetic seal. See Note under Hermetically. Hermetic art, alchemy. Hermetic books.

   1. Books of the Egyptians, which treat of astrology.

   2. Books which treat of universal principles, of the nature and orders of celestial beings, of medicine, and other topics.