What was the significance of Jesus' instructions to the disciples at Transfiguration?

We see the instruction given to the three disciples who accompanied Jesus to the site of Transfiguration at Mtt 17:19 : > As they were coming down the mountain, Jesus ordered them, “Tell no > one about the vision until after the Son of Man has been raised from > the dead. But then, we also see at Mtt 26:63-64, Jesus publicly disclosing his divinity to the High Priest during his trial: > But Jesus was silent. And the high priest said to him, “I adjure > you by the living God, tell us if you are the Christ, the Son of God.” > Jesus said to him, “You have said so. But I tell you, hereafter you > will see the Son of man seated at the right hand of Power, and coming > on the clouds of heaven.” Now, it would have been really hard for the three disciples to keep to themselves the secret regarding Jesus' Transfiguration, between the period of his death and resurrection, knowing that such a disclosure would bring a ray of hope to the other disciples who had lost heart at the loss of their Master. My question therefore, is: was there a special significance to the instruction of Jesus to the disciples who witnessed his transfiguration ? What do the teachings of Catholic Church say about it ?