The Fourth Sunday of Easter is traditionally known as "Good Shepherd Sunday" in reference to the Gospel of the day—always a passage from John Chapter 10—in which Jesus describes Himself as the Good Shepherd.
“You are witnesses of these things” (Lk. 24:48). The Apostles, who saw with their own eyes the Risen Christ, could not keep silent about their extraordinary experience. He had revealed himself to them so that the truth of His Resurrection could reach everyone through their witness.
The Second Sunday of Easter is called “Divine Mercy Sunday.” The message of the Divine Mercy is directly connected to the celebration of the Paschal Mystery.