As we know, there are seven principal vices from which all other infectious forms of vice derive, namely: pride, avarice, vainglory, anger, envy, lust, spiritual torpor. These, moreover, since they are the cause and origin of all evils, are known to have the same number of effects, namely, the seven mortal sins, that is, adultery, murder, theft, perjury, false witness, plunder, and blasphemy. in each of these the death of the soul is so clear and certain that if anyone should die guilty of any of them, he could not possibly avoid the sentence of eternal damnation. There are also seven slight or minor sins into which not only the sinner but also every upright man falls daily, even though he might appear to stand at the very peak of perfection. These, accordingly, are sins of thought, ignorance, inconstancy, necessity, infirmity, forgetfulness, surprise. Because of these, surely we always fail our everyday living, and so against the wounds of sin we need some daily remedy for their cure.[Peter Damian, The Letters of Peter Damian, 1-30, Blum, tr., The Fathers of the Church: Medieval Continuation, Catholic University Press (Washington, DC: 1989) p. 146.]
The seven principal vices, of course, are as the capital vices usually are. The 'seven mortal sins' are (I take it) a condensation of the Ten Commandments. I don't think I've come across the list of 'seven slight or minor sins', but from the list, this could be just because this is an unusual way of expressing the subject -- what the list is really describing are circumstances that can often make a grave sin a venial one, so they aren't really specific sins, but seven ways any sin could become 'slight or minor', and thus a form of wrongdoing that we find even in just persons.
