Paracelsus's life was one of endless writing. The picture on the left shows one of the few autograph documents which is preserved in the Stiftsarchiv St. Gallen: the "Consilium" he gave to abbot Johann Jakob Russinger of Pfäfers in 1535.

His complete works sum up to about thirty large volumes, not included the probably numerous lost writings. Nevertheless, during his lifetime only a few of them went to press: some astrological prognostications, a description of the spa of Pfäfers, a couple of books on syphilis and as most comprehensive work his "Grosse Wundarznei" (Great Surgery).

The rest was banned from the printing press, certainly due to the fact that Paracelsus was an inconvenient writer whose reforms and criticism were not estimated.

In the 1560s, only twenty years after his death, there was an awakening of interest in Paracelsus's teachings which resulted in numerous print editions, culminating in the great edition of the collected medical and philosophical works by Johannes Huser in the years from 1589 to 1591.

Regardless of the historical and biographical background, the following systematic subdivision represents an attempt to grasp the complex diversity of Paracelsus's writings.:

1. Natural Philosophy, Alchemy and Pharmaceutics

In these writings Paracelsus describes plants, minerals, sulfuric acid, mercury, turpentine and other natural materials. He comments on the transformation of metalls and gives in "De modo pharmacandi" a theory of administration. The "Nine Books of Archidoxes" present an early theory of medical alchemy basing on the medieval concepts of alchemy.

2. Description of Diseases

Numerous writings describe various diseases and their treatment such as syphilis, the plague, jaundice, smallpox and epilepsy. The tartaric diseases, as they were called by Paracelsus, concern metabolic disorders effected by sedimentations in the body, such as gout or calculus in the kidneys and the bladder. The miners suffer a specific disease when they inhale toxic vapors from the mines and smelting furnaces. As "invisible diseases" Paracelsus even had described mental illnesses.

3. Theory of Medicine

Above all Paracelsus's writings on the theory of medicine became famous, in which he programmatically outlined the main features of his vision of a new medicine. In his early "Volumen medicinae paramirum" he sketched the five entia or causes of medicine. The ens astrale stands for the influence of the stars, the ens veneni concerns the action of obvious or hidden poisons and the ens naturale delineates natural causes leading to sickness. When the disease is brought forth by evil spirits, then the interaction is called ens spirituale, and when the cause can be traced back only to God himself, then it becomes ens dei.

In the book "Paragranum" (1530) Paracelsus describes the four pillars of medicine: natural philosophy as the science of the things dwelling in nature, astronomy as the science of the interplay between cosmos and humans, alchemy as the science of the purification and transformation of matter and especially of drugs, and finally the virtue or the ethics of the physician.

In the "Opus paramirum" (1531) Paracelsus goes on to outline his vast vision of a new medicine, presenting a theory of the pathogenic action of the three primary substances sulphur, mercury and salt, in addition a theory of the primordial matrix as generalization of the maternal womb, and finally a theory of the above mentioned tartaric diseases. Among the theoretical writings there are also a treatise on urine, a commentary on the aphorisms of Hippocrats and other things.

4. Surgery

A large part of the medical writings relate to surgery such as the "Berthonea" or "Chirurgia minor", the book "Von allen offnen Schäden" (On all open defects) and the "Große Wundarznei" (Great Surgery, 1536). Surgery in medieval and early modern times involved above all the treatment of wounds, abscesses, fistulas, rashes and other skin diseases rather than the application of surgical operations. The surgical writings contain a large number of clinical observations and detailed prescriptions.

5. Description of Spas

It was customary for physicians to give descriptions of spas and their salutary effects. Paracelsus's description of the famous Pfäfers spa was even printed in his lifetime (1535). Similar treatises are "Von den natürlichen Bädern" (Of Natural Spas) and "Von den natürlichen Wassern" (Of natural waters).

6. Divination and Prophecy

These writings present predictions and prophecies which were based on the observation of planets, comets, solar eclipses, exceptional rainbows and other heavenly constellations. The astronomical casting of annual prognostications in the form of calendars meant a significant contribution to many a physician's income. Following this tradition, Paracelsus wrote some ten prognostications printed in his lifetime. He also wrote commentaries to two well known series of prophetic emblematic images, the "Nürnberger Figuren" and the "Vaticinia pontificum".

7. Natural Magic

Not insignificant are the magical writings which are presupposing an invisible, magical side of nature with ghosts, nature spirits and demons, in fact a world not contradicting with Biblical issues. For the Renaissance mind, natural magic was nothing but a seemingly logic extrapolation of natural philosophy to invisible realms. Whereas Paracelsus's "Philosophia magna" and the possibly inauthentic "Occulta philosophia" describe various single topics of the magic world view, the "Astronomia magna" or "Philosophia sagax" (Philosophy of the Wise, 1537/38) tries to give a vast synthesis of natural philosophy, magic and theology. If this immense work would have been completed by Paracelsus and published earlier, it could have performed a considerable impact on the prescientific views of the 16th century.

8. Theology

Essentially, Paracelsus's theological writings are commentaries to the Bible, so to the Book of Daniel, to the prophet Isaiah and to the Ten Commandments. The commentaries to the Psalms and to the Gospel of St. Matthew even belong to the most voluminous of the complete works. Paracelsus dealt with current issues of the church reformation as baptism, penitence, matrimony and Christian ethics with all its social impact. Further writings treat of the "Vita Beata", the beatific life to be attained already on earth in anticipation of eternal life, then of the Virgin Mary and of the Eucharist. As to the healings, miracles and exorcisms described in the Gospels, Paracelsus tried to imbed them in his world view, which based on natural philosophy and magic.

9. The Carinthian Writings

The late so called "Carinthian Writings" (1537/38) consist of the "Book of Tartaric Diseases", the "Septem Defensiones" (Seven Defensions) and the "Labyrinthum medicorum errantium" (Labyrinth of Erring Physicians). Paracelsus summarizes here the key points of his teachings and defends his peculiar way of thinking. The officials of Carinthia, the former residence of his father and the place of his latter boyhood, had promised to publish these writings without delay, but finally reneged.

10. The Basel Lectures

In his short time in Basel 1527/28 as a professor of medicine, Paracelsus released a literal intellectual firework and presented a whole series of lectures covering variant topics. Some of them have been preserved as lecture notes by students. They convey a vivid impression of how Paracelsus had taught.

11. Spurious Writings

Several treatises, mostly written at the end of the 16th century, have been falsely attributed to Paracelsus in order to achieve greater sales success. They mostly concern transmutational alchemy and magic with titles like "Libellus de tinctura physicorum", "Thesaurus thesaurorum alchemistarum", "Coelum philosophorum", "Manuale de lapide philosophico", "Ratio extrahendi ex omnibus metallis mercurium", "Archidoxis magica" and "Liber principiorum". Although most of these tracts are doubtlessly spurious, they were considered to be authentic in the reception. They helped to form erroneous picture of Paracelsus as a goldmaker and magician.