When I started attending traditional Masses in 2005, I thought the Mass was a community celebration; basically a love-in with a commemoration of the Last Supper. Then, at a catechism class given by Fr. Michael Weiner of the Institute of Christ the King, I heard that the Mass is a Sacrifice. I had no idea what he was talking about. The reason was that the Novus Ordo does not ordain Sacrificing priests, and they do not have any intention of doing so. That is why NO ordinations are invalid.