This is Thomas Aquinas making moral sense (though some considerations of economic pragmatism need to be taken into account atop these basic moral principles).
Now, according to the natural order instituted by divine providence, material goods are provided for the satisfaction of human needs. Therefore the division and appropriation of property, which proceeds from human law, must not hinder the satisfaction of man’s necessity from such goods. Equally, whatever a man has in superabundance is owed, of natural right, to the poor for their sustenance. So Ambrosius says, and it is also to be found in the Decretum Graziani “The bread which you withhold belongs to the hungry; the clothing you shut away, to the naked; and the money you bury in the earth is the redemption and freedom of the penniless.”
via Think Tonk.