"The universal destination of all material goods is in God. As Aquinas says, we should regard property as a gift from God, a gift that is only valid if we use it for the benefit of others. Thus Aquinas sanctions private ownership only insofar as it is put to its proper end, which is the good of all: 'Man ought to possess external things, not as his own, but as common, so that, to wit, he is ready to communicate them to others in their need.'
Absent such a view of the true end of property, freedom means being able to do whatever one wants with one's property, and property can thus become nothing more than a means of power over others."
(William Cavanaugh, Being Consumed, p. 29)
I would suggest that Cavanaugh's comments should be extended not only to material goods, but all materials that we "possess" as humans, and that includes our most obvious possessions: our very selves - body and mind. We are not our own - this means that our "ownership" of ourselves is in question if we are not turning ourselves toward our true end, namely, the benefit of others. Jesus called this simply "loving your neighbor." Without such a turning, our bodies and minds can be, to quote Cavanaugh again, "nothing more than a means of power over others."