'Perfection' in the Bible

Hath not thy piety been thy confidence, and the perfection of thy ways thy hope?

Canst thou by searching find out +God? canst thou find out the Almighty to perfection?

Out of Zion, the perfection of beauty, God hath shined forth.

I have seen an end of all perfection: thy commandment is exceeding broad.

All that pass by clap their hands at thee; they hiss and shake their head at the daughter of Jerusalem: Is this the city which they called, The perfection of beauty, The joy of the whole earth?

Son of man, take up a lamentation upon the king of Tyre, and say unto him, Thus saith the Lord Jehovah: Thou, who sealest up the measure of perfection, full of wisdom and perfect in beauty,

But that that fell where the thorns were, these are they who having heard go away and are choked under cares and riches and pleasures of life, and bring no fruit to perfection.

If indeed then perfection were by the Levitical priesthood, for the people had their law given to them in connexion with it, what need was there still that a different priest should arise according to the order of Melchisedec, and not be named after the order of Aaron?