The Wikipedia page on the Decameron claims that:
Many details of the Decameron are infused with a medieval sense of numerological and mystical significance. For example, it is widely believed[by whom?] that the seven young women are meant to represent the Four Cardinal Virtues (Prudence, Justice, Temperance, and Fortitude) and the Three Theological Virtues (Faith, Hope, and Charity). It is further supposed[by whom?] that the three men represent the classical Greek tripartite division of the soul (Reason, Spirit, and Appetite, see Book IV of Republic).
As indicated by the "by whom?" markers, this claim is rather vaguely made and not clearly supported. I'm not so much interested in the question of by whom, but rather the question of why this is believed and how plausible it is. What's the evidence to support this reading of the characters?
Do the seven women and three men really represent the Cardinal Virtues, Theological Virtues, and division of the soul? What evidence supports this reading of the characters, how widely believed is it, and how plausible is it, taking into account the content of the text, the beliefs of the author, and the context of the times in which he was writing?