Rest in peace (acronym R.I.P.) in the second person singular, or “Requiescite in pace” in the second person plural. In the common phrase "Requiescat in pace" the "-at" ending is appropriate because the verb is a third-person singular present active subjunctive used in a hortative sense: "May he/she rest in peace." The phrase was first found on tombstones some time before the fifth century. It became ubiquitous on the tombs of Christians in the 18th century, and for High Church Anglicans, Methodists, as well as Roman Catholics in particular, it was a prayerful request that their soul should find peace in the afterlife.
Common Era "before the beginning of the vulgar æra, by which we now compute the years from his incarnation." A 1796 book uses the term "vulgar era of the nativity". The first so-far-discovered usage of "Christian Era" is as the Latin phrase "aerae christianae" on the title page of a 1584 theology book. In 1649, the Latin phrase "æræ Christianæ" appeared in the title of an English almanac. A 1652 ephemeris is the first instance so-far-found for English usage of "Christian Era". The English phrase "common Era" appears at least as early as 1708, and in a 1715 book on astronomy is