I spent yesterday evening, on the recommendation of Carl Trueman, reading a delightful little book on Natural Law, by David Haines and Andrew Fulford.
Before I begin, I have two confessions to make: I'm a General Revelation (GR) fan but a Natural Law (NL) sceptic; I am not Aquinasian (Thomist sounds too stodgy).
Citing theology and Scripture, the authors insist, that in observation, intuition and reason, people in all lands, made in the divine image, by nature do know God.
Such light, cannot save, and is largely suppressed or ignored: yet, not only can ants teach anthropoids how to work, but the Gospel goal is to fix-up Genesis Lost.
That implies, evidently, that liturgy, family and industry lie at the heart of humanity - it also hints that even pagans realize people need weekly, holy, rest.
If Moses and Jesus teach which day to keep, Sabbath-Keeping, by nature, is simply commonsense: saints in all lands should apologize less and enjoy weekly rest.