Many don't realize that the 40 days of Lent from Ash Wednesday to Easter Sunday actually span 6 1/2 weeks, or 46 days inclusive.
How does one get 40 days out of 46?
It's illegal to fast on Sunday. Thus the whole Easter season is intended to be a glorification and an exaltation of Sunday.
The church of the east celebrated Christ's death and resurrection on Nisan 14, the Passover. Bishop Victor of Rome in the second century excommunicated the entire church of the east since they wouldn't celebrate Easter on a Sunday. But he didn't have the power to get away with that. they simply turned around and excommunicated him.
Once Rome gained in power, civil laws were passed against the Quartodecimians, those who remembered Christ's death and resurrection on Nisan 14 instead of Easter Sunday. But from what I recall, Rome's insistence that one can fast on Sabbath but can't fast on Sunday was still a point of controversy between east and west for centuries afterwards.
But today, no one seems to notice that the 40 days of Lent are really 46, and no one seems to notice that fasting on Sabbath is commanded, and fasting on Sunday is prohibited.