The Mutus Liber is an epistemological treatise. The alchemical laboratory is the mind, as proved by the first plate: the illustration of the Biblical dream of Jacob (Gen. 27:28.39, 28:11.12, Deut. 33:18.28). No one can deny that dreams are in the mind. In it, ideas are chemical compounds and their processes are reactions producing thoughts and knowledge. The operation and the alchemical transmutation takes place and is registered in the mind, by the mind and through the mind in all its stages, conscious, subconscious, unconscious and beyond. Therefore, the key to interpret the plates and to open the mouth of the Mute Book (as in the Egyptian tradition) is gnoseological and not related to any New Age perspective. The chemical elements, consequently, are only metaphors (as in the parable's of Biblical tradition) to describe real epistemic processes which establish the world into existence (as in the Indian tradition). One can have millions of alchemical laboratories with expensive equipment but without the mind no one can achieve any transmutation at all. Furthermore, no physical alchemical transmutation persists for the practitioner in the sleep of death. Mutus Liber concludes inviting Eternal Life (as in the Chinese tradition) understood through prayer (as in the monastic ora et labora). This commentary completes with an extensive quoted and studied bibliography of the original first edition of Altus' plates as well as works by Jung, McLean, Magophon, Canseliet and many others.