From The Art and Popular Culture Encyclopedia
Petrus Forestus was the son of Jorden van Foreest and Margriet, daughter of Nanning Beyers. He received his early schooling at the Alkmaar Latin School. Around 1536 he started studying at the University of Leuven. In 1540 he began a so-called peregrinatio Academica, an educational journey in which he visited several European universities in order to acquire detailed knowledge of medicine. He stayed three years in Bologna, from which he also worked in Padua, Venice, and Ferrara. On 29 November 1543 he graduated at the University of Bologna. Then he worked for some time in Rome and Paris. In 1546 he returned to Alkmaar, where he opened a medical practice. He married in 1546 with Eva van Teijlingen (1525 – 1595).
In 1558 Forestus was appointed to the post of city physician of Delft, a function he performed for over 37 years. In August 1574, during the siege of Leiden, Forestus was consulted by prince William of Orange, who lay ill in bed at Delfshaven. Since then Forestus was repeatedly consulted by members of the princely family when they were afflicted by disease.
Forestus was invited by the Curators of the newly founded Leiden University to attend the opening ceremony on February 8, 1575. He participated in the festive procession as "doctor and professor of medicine" and stayed in Leiden until February 12 in order to sign the Statutes of the new university. After that he returned to Delft. He prefered his medical practice, and decided not to take up an academic position.
After the assassination of Prince William of Orange on July 10, 1584, Forestus conducted the autopsy and embalming together with his colleague from Delft, Cornelius Busennius. They made an extensive report of the autopsy to the States of Holland.
Petrus Forestus died on 10 March, 1597. He has over 75 years old. His remains were buried in the Great or St. Lawrence Church in Alkmaar on March 13 1597. The last line on his tombstone reads: Hippocrates batavus si fuit ille fuit (If ever there was a Hollandic Hippocrates, it was this man).
Forestus had a deep aversion to quacks, charlatans, and the unauthorized practice of medicine. Part of a preserved unpublished manuscript was titled: Vander Empiriken, Landloeperen ende Valscher Medicynsbedroch (On charlatans, frauds, and the trickery and deceit with false medicine). He had written this manuscript on behalf of simple people, who were often the target of such frauds and deceptions. In 1584 he managed to convince the Delft magistrates to place rules and restrictions on the practice of medicine.
During his practice years in Alkmaar, Forestus began to take notes on the maladies of his patients, and how he treated them. Later he arranged the data and eventually collected over 1350 Observationes with appropriate Scholia. The Observationes were more than the literal meaning "things seen" indicates. They were very personal perceptions of patients and diseases. They form the basis for subsequent Scholia, which can be regarded as the academic treatises of a doctor medicinae who had studied at the most renowned Italian universities. This data was initially dedicated as a separate monograph to personal acquaintances such as Prince Maurice of Orange, and city governments, like those of Alkmaar, Delft, Leiden, Amsterdam and Enkhuizen. In 1609 all monographs and the treatise on urinalysis were bundled and published in Frankfurt as the Opera Omnia. numerous reprints followed.