Pope St. Gregory the Great († 604)

"At that hour of the Sacrifice, at the words of the Priest, the heavens are opened, and in that mystery of Jesus Christ, the choirs of Angels are present, and things below are joined to things on high, earthly things to heavenly, and the service is both a visible and an invisible event."

Many thanks Argent by the Tiber.

You can say this 100 percent of the time about the traditional Latin Mass. Other Masses, I would not dare to fix a percentage. But it is less than 100, perhaps much less.