I answer that, The
Old Law showed forth the precepts of the
natural law, and added certain precepts of its own. Accordingly, as to those precepts of the
natural law contained in the
Old Law, all were bound to observe the
Old Law; not because they belonged to the
Old Law, but because they belonged to the
natural law. But as to those precepts which were added by the
Old Law, they were not binding on save the Jewish people alone.
The reason of this is because the
Old Law, as stated above (
Article 4), was given to the Jewish people, that it might receive a prerogative of
holiness, in reverence for
Christ Who was to be born of that people. Now whatever laws are enacted for the special sanctification of certain ones, are binding on them alone: thus
clerics who are set aside for the service of
God are bound to certain
obligations to which the
laity are not bound; likewise religious are bound by their profession to certain works of perfection, to which people living in the world are not bound. In like manner this people was bound to certain special observances, to which other peoples were not bound. Wherefore it is written (
Deuteronomy 18:13): "Thou shalt be perfect and without spot before the
Lord thy God": and for this reason they used a kind of form of profession, as appears from
Deuteronomy 26:3: "I profess this day before the
Lord thy God," etc.