Sometimes Christians are very Semitic. Sometimes, it seems. The next day begins at sundown of the previous day. Is this not the rationale for the Roman Catholic Saturday evening Masses that "count" as Sunday service? Is this not the rationale for monasteries in both West and East in fact celebrating sundown services early in a fasting day to reduce the number of hours of fasting? ("We have celebrated Vespers, it is the next day -- let us feast!")
"Anticipation" has brought believers to think that Christ was Crucified on Holy Thursday and arose on Saturday, according to the Greek author addressing the Liturgical "problems" of Holy Week in the Orthodox Tradition in the recent edition of St. Vladimir's Theological Quarterly.
Any clarification as to when in the course of a secular calendar day (midnight to midnight) the next Liturgical day should be considered to start, and when it does not start, would be greatly appreciated. (In other words, when is "anticipation" O.K. and not O.K.?)