Did your parents or teachers ever drill something into you when you were a kid so that you couldn't forget it? I'm guessing that most of us would answer yes. I think it's that way with the Scriptures, too. When something is repeated often and insistently in Scripture, you get the feeling that we had better pay close attention and take it very seriously!
Easter is about victory! God the Father raises his Son Jesus from the humiliation and apparent defeat of the cruel death by crucifixion. Jesus is raised to a new life in the resurrection. Jesus is then raised from the earth to heaven in the ascension. God exalts Jesus to his right hand, where he pours out the Holy Spirit upon his followers, and from thence he will come to judge the living and the dead. God exalted him...let us exalt Jesus as well!
This Sunday has been called by many names. Perhaps the earliest was The Octave of Easter. It was also called Dominica in albis, referring to the practice of the newly baptized at Easter laying aside their white baptismal garments on this day. It has also been known as Quasimodo Sunday, after the Introit verse in Latin ("As newborn babes, crave pure spiritual milk"). It was also popularly called "Low Sunday," in contrast to the "high" celebration of Easter a week ago.
"You are dupes! I am a liar! Your faith is foolish! And you are still in your sins!" I still remember Easter homilies starting out that way for years at St. Joseph Seminary, before Abbot Columban paused and added, "If Christ is not risen." His reference to St. Paul's statement in 1 Corinthians 15:17 usually grabbed everyone's attention! It does get across the point that everything - absolutely everything - depends upon the resurrection of Jesus, which is what we celebrate today.
We know that our life on earth is filled with transitions. The liturgy today, Palm Sunday, also describes some swift transitions in the life of Jesus, especially in the space of one week...which we now refer to as Holy Week.