In the line, as many degrees are counted as there are generations or persons, excluding the progenitor.
In the direct line, ascent is made to the common ancestor. Thus, the child is one degree removed from the parent, two from the grandfather, and three from the great-grandparent.
In the collateral line, ascent is made to the common ancestor and then descent is made to the person with whom the computation is to be made. Thus, a person is two degrees removed from his brother, three from his uncle, who is the brother of his father, four from his first cousin, and so forth. (918a)