Hebrews 8:4

If then he were on earth, he would not be a priest. He speaks of a priest according to the custom of the Jews, where none were priests but of the tribe of Levi, and Jesus Christ was of the tribe of Juda: and if the law of Moses was to continue, there would not be wanting priests to offer sacrifices according to their worship, though such priests were only employed about things that were types[2] and shadows of heavenly things in the new law after Christ's coming, and of the sacrifices by which he offered himself on the cross. And this God doubtless revealed to Moses, when he said to him: take heed "thou make all things according to the pattern which was shewn thee on the mount." (Witham) --- Earth, &c. That is, if he were not of a higher condition than the Levitical order of earthly priests, and had not another kind of sacrifice to offer, he should be excluded by them from the priesthood, and its functions, which by the law were appropriated to their tribe. (Challoner)

[BIBLIOGRAPHY]

Exemplari et umbræ deserviunt, Greek: upodeigmati, kai skia latreuousi. It signifies, that they served God by those things that were types and figures of more perfect and heavenly things.