In the medieval commentaries on Genesis 3:1 and in the art of the 13th-17th century, the Edenic tempter is often visualized as having a maiden's face. The author argues that this feminization of the serpent means that the sin is defined as a 'representation'. In Part I, the author examines the late ancient discourse on the evil. Plotin, who identifies the evil with the matter as the non-being - intelligible only in the 'bastard' way (gr. notho) - metaphorizes it as the 'femininity': he reminds the comparison of Aristote (Phys. 192a), and the Plato's figure of Poverty (Penia) (Conv. 203). The Plato's story is associated by Orygenes and Eusebius with the Genesis words. They identify Penia with the Edenic serpent, in such way defining Eva's status: her being is understood as 'lack', privatio, perceivable only by looking awry, thanks to the serpent which is the bastard cognitive instrument. In Part II, the author examines the formulations of medieval exegetes: 'similia similibus applaudunt and similitudo mater est falsitatis'. The sin as seduction means here: (1) the rhetoric language feminization (the corruption of the primar lingua humana by opening the ability for verbal deceit) and (2) deceptive similitude, which not relates (referre) to the truth of the prototype but closes the image in the mirror feedback. The whole contribution is closed by some observations about the medieval misogynism (a woman as senses and symptom of the man).