The year 2021 marks the 1,700th anniversary of the consecration of Sunday as a weekly day of rest. Having become a precept of the Church, this institution has received many blows from the French Revolution to the present day.
The Justinian Code, a collection of imperial constitutions promulgated since Hadrian, and published in 528, traces Sunday rest to the Emperor St. Constantine.
Indeed, in the spring of 321, less than ten years after the victory of the Milvian Bridge which was an essential step on the road to power and his conversion to Christianity, the son of Constance Chlore and St. Helena addressed the vicar of Rome in these terms: “that all the judges, the urban plebs, the services of all the professions rest on the venerable day of the Sun” (Justinian code, III, XII, 2).
The emperor returned three months later, on July 3, 321, to the subject by insisting once again on the respect due to the first day of the week, evoking “the day of the Sun, consecrated by its veneration” (Theodosian code, II , VIII, 1).
The day of rest was not yet called “dies dominicus” or “Lord's day” by Constantine, but “day of the Sun” in reference to the “Undefeated Sun,” a name dear to the old Romans to designate the first day of the week.*
But make no mistake, it was the Christian faith, which would lead Constantine at the end of his life to ask for baptism, which inspired such a measure from the conqueror of Maxentius at the Milvian Bridge.
This notion of rest was still quite flexible: “In the country, however, persons engaged in agriculture may freely and lawfully continue their pursuits; because it often happens that another day is not so suitable for grain-sowing or vine-planting; lest by neglecting the proper moment for such operations the bounty of heaven should be lost,” says Constantine.
On the Church side, the oldest ecclesiastical law that has come down to us on this point is a canon of the Council of Laodicea, the date of which is uncertain, but which can be placed around A.D. 364.
The council ordered abstinence from work on Sundays “as much as possible,” a formula which suggests that the custom was still rather flexible.
Beginning with the reign of the emperor Theodosius (379-395), the reference to the sun gradually faded and passed from “the day of the sun, ritually called by our ancestors the day of the Lord [dies dominicus], which gets its name from what it represents.”
From the 6th century on, we see a proliferation of special councils that recalled the duty of Sunday rest and the days of obligation, all over the Church, up to St. Thomas Aquinas who systematized this doctrine, guided by the principle according to which servile works are prohibited insofar as they prevent man from applying himself to divine things.
We had to wait for the French Revolution to see Sunday rest attacked, in particular with the implementation of the “decadi.” The revolutionaries indeed established 10-day weeks, the last of which, the Decadi, was a nonworking day. This foolishness lasted less than 15 years.
Since the institution of Sunday rest continues to suffer attacks: sometimes attacked head-on and suppressed, sometimes rehabilitated, or trimmed as evidenced by the Macron Law of 2015—which extended the hours businesses may be open—named after the current president of France, who was at the time François Hollande's Minister of Finance.
[This is more obvious in countries with Latin-based languages, where the name of the day of the week has its root in the Latin “die dominicus”: the French, dimanche; the Spanish, domingo; the Italian, domenica. The Germanic languages retained the reference to the sun: the German, Sonntag, the English, Sunday, etc. – Trans. Note.]