The disappearance of the technical notion ofspeciesin Montaignes’sEssaysis characteristic of the transformation that took place around the beginning of the trial of knowledge. The theory of the species is then replaced by a doctrine of the appearance as “fantasy”. The problem, which is epistemological, takes its source in the debate opposing Stoics, Neo-academicians and Pyrrhonists on the topic of the truth value of representation. The conclusive passages in theApologyenable us to grasp the neo-pyrrhonian problematic in all its complexity. In it, (...) Montaigne focuses on the difference between appearance and reality, or appearance and essence, by opposing — as Sextus did — the “nature”, in itself inaccessible, to the quality as we perceive it through our senses. The role of the senses in this process is described either as a qualification or alteration of the object, or as a “falsification” of it, which entails the classical sceptical problem of the difficulty to choose between one representation or another — and to discriminate between the qualities that are “normal” and those that are not. A comparison with Henri Estienne’s commentary to thePyrrhonianae Hypotyposesfinally sheds some light on Montaigne’s dependence toward Greek sources and Renaissance philology. (shrink)