The liberality of the neo-Fregean account of ontological commitment is best appreciated by considering its application to abstraction principles for which, unlike Hume's Principle, the right-hand side appears to be entirely about concrete entities, and so appears to be acceptable to a nominalist. For example, consider the abstraction principle for directions: the direction of line a is identical to the direction of line b if and only if a is parallel to b (where a and b are concrete). According to the neo-Fregean account, the claim that concrete lines a and b are parallel is committed, by itself, to abstract objects, directions.[46] Moreover, it has this commitment whether or not any mind ever grasps the concept of direction, or formulates the corresponding abstraction principle. In general, commitments to abstracta are concomitant with certain commitments to concreta, and inseparable from them, regardless of our ways of conceptualizing.[47]