Tomorrow is the day Christians mark the coming of the Holy Spirit to a bunch of scared guys in a room- and the Church's birthday.
Jesus had gone to heaven, but they were still worried about the Jewish authorities. Then the room turns distinctly flamy and tongues of fire land on all of their heads.
They're transformed after this, speaking in dozens of languages to a large crowd- the disciples don't do public speaking before that, I believe.
They were transformed by one element of the Trinity, that still transforms people today.