The article is an attempt to demonstrate the role of mind (νούς) when a human being commits a sin, according to the teaching of St. Maximus the Confessor, while the function of mind was analysed by Aristotle, centuries ago. The author, at first, clarifies the relation of sin to the God’s creation, based on St Maximus’s theology. After that, he presents the Maximian division of the sinners, into unwilling (αδιαθέτως) and willing (ενδιαθέτως) sinners, and he tries to explain how the mind works in the passionate world of the second ones, by using the senses, the imagination and the memory. Finally, he deals with the Aristotle’s notion of mind, such as its definition, its functional division and the usage of sensation, imagination and memory while it acts (νοείν).