The Lord's Day is a mystery of the knowledge of the truth that is not received by flesh and blood, and it transcends speculations. In this age there is no eighth day, nor is there a true Sabbath. For he who said that `God rested on the seventh day,' signified the rest [of our nature] from the course of this life, since the grave is also of a bodily nature and belongs to this world. Six days are accomplished in the husbandry of life by means of keeping the commandments; the seventh is spent entirely in the grave; and the eighth is the departure from it.
St. Isaac of Syria, The Ascetical Homilies.I