Source edition
Galen. Claudii Galeni Opera Omnia, Volume 5. Kühn, Karl Gottlob, editor. Leipzig: Knobloch, 1823.
Source data
A Digital Corpus for Graeco-Arabic Studies · CC BY-SA 4.0
Cloned and adapted by Humanitext, with ongoing edits.
Summary
This philosophical and scientific treatise addresses how to avoid errors in the human soul and achieve true knowledge. Galen criticizes the rashness of contemporary philosophers who rush into unverifiable cosmic questions, arguing that avoiding error requires rigorous and long-term training in verifiable disciplines like geometry and architecture. Through concrete practical examples such as the construction of sundials and water clocks, he demonstrates the necessity of analytical and synthetic demonstrative methods. The text sharply contrasts the dogmatic assertions of untrained know-it-alls (doxosophoi) from various philosophical schools with the precise, evidence-based methods of practical craftsmen. Ultimately, the work advocates for suspending judgment (epoché) until sufficiently clear evidence is attained by both senses and reason, establishing a disciplined path to reliable knowledge.