How may we characterize the intellectual world in which Paracelsus lived? Surely a major factor was Renaissance humanism -- the fascination with antiquity in all of its aspects. Authors sought to write a stylistically pure Latin to replace the barbarous Latin of the Middle Ages. They travelled in search of old manuscripts that might have survived in isolated monasteries ... and they studied Greek so that they might translate these treasures of the ancient world. This search for the work of ancient authors was felt first in literature, rhetoric and history, but by the late fifteenth century there was an increasing interest in the sciences and medicine. Astronomers and mathematicians sought an accurate text of Ptolemy's Almagest and both the observations and the mathematics of this text were to form the foundation for Copernicus' De revolutionibus orbium (1543). In medicine Galen, Hipprocates, and Dioscorides were newly translated from Greek. The recovery of the medical writings of Celsus was highly influential because they presented medical terminology in the elegant Latin of the first century A.D. Indeed, for many humanists the discovery of new texts seemed as exciting as the discovery of the new lands being made by contemporary explorers. The result was a new reliance on the truths of antiquity and establishment medicine became increasingly dependent upon the writings of Galen, the "Prince of Physicians." In short, with the corrected translations of ancient authors -- and more important, the discovery of new manuscripts lost to scholars for a thousand years -- it was thought possible to restore the real truths of both Aristotelian natural philosophy and Galenic medicine.
Numerous Renaissance physicians favored the teachings of Hippocrates over those of Galen. From Justi Cortnummii, Di morbo attonito liber unus ad Hippocraticam... (Lipsiae, 1677).
However, the recovery of ancient classics and their translation was not limited to the works of Aristotle, Galen, Ptolemy, and Dioscorides. In addition to the works of many lesser figures there were new areas of study made available to Renaissance scholars. Important among them was the recovery of the Corpus Hermeticum, a group of treatises supposedly written in Egypt by Hermes Trismegistus at about the time of Abraham although they had not been composed until late antiquity. Authors of these treatises felt that a magus, a true natural magician, would be able to understand man, the microcosm, through his study of the macrocosm since the former was a perfect representation of the latter. Some physicians were to find this a new key to their work. No less appealing was the fact that this call for new observations in nature could be seen as an act of devotion. Christians should study not only Holy Scripture, but also the book of nature, clearly a second book of divine revelation.
Hermes was known not only to the Church Fathers, but also as one of the great figures of alchemy. Even today we speak of a hermetic seal in chemistry. Traditional alchemy did include a belief in the transmutation of the base metals to gold, but more important was the separation by chemical means of the pure essence of a substance from its impurities. Through such processes (frequently through distillation) the true divine signatures impressed on earthly things by the Creator for their proper use (and then lost at the time of the Fall) might be rediscovered. In this fashion we would learn more of our Creator while recovering His gifts through our labor. Surely we could expect to find substances of medicinal value in this way.
In short, by 1500 the impact of the newly recovered texts was leading in two directions. On the one hand the natural philosophers and physicians of the schools had developed an increased respect for Aristotle, Galen and other ancient authorities. On the other hand, the recovery of the Corpus Hermeticum and other more mystical texts placed an emphasis on natural magic, the relationship of man to the macrocosm, and sought divine truths in the study of nature. The first path led to truth through traditional medicine and a reliance on mathematics and the physics of motion for our understanding of nature: the second led to a more mystical and religious basis of knowledge and turned to chemistry as a key to man and nature alike.