3 types of actual sin
The division of sin into original and actual, mortal and venial, is not a division of genus into species because sin has not the same signification when applied to original and personal sin, mortal and venial. Mortal sin cuts us off entirely from our true last end; venial sin only impedes us in its attainment.ince sin is a moral evil, it is necessary in the first place to determine what is meant by evil, and in particular by moral evil. Evil is defined by St. Thomas (De malo, 2:2) as a privation of form or order or due measure.