The description of an anatomical specimen may look straightforward, but it appears that it depends in fact on several intermingled factors: technical methods for conservation, dissection and vascular injection and the anatomist skills are of course important. This is especially true when the studied organ, as for instance the brain, is subject to rapid putrefaction after death without any preservation technique. Nevertheless the possibility to reject, or at least criticize, the dominant paradigm is probably as important as these technical considerations: important changes occurred in brain representation between the early Middle Ages and the Early Modern Times, without major improvements of cadaveric preservation or dissection methods; Vesalius rejected the existence of the rete mirabile in human not only because he was a talented anatomist but also because he accepted and had the courage to fight the dominant tradition inherited from Galen. Such difficulties in the scientific approach obviously remain vivid, and should not be forgotten despite the development of modern tools for studying brain morphology and function.