Priestly Garments

And you shall make sacred garments for Aaron your brother, for honor and for beauty. And you shall speak to all who are wise hearted, whom I have filled with the spirit of wisdom, that they may make Aaron’s garments to consecrate him, that he may minister to me in the priest’s office. And these are the garments which they shall make: a breastplate, and an ephod, and a robe, and a quilted undercoat, a mitre, and a girdle; and they shall make holy garments for Aaron your brother, and his sons, that he may minister to me in the priest’s office …” (Ex. 28:2–4)

"Moses was instructed by [God] that the garments of the priests were to be both dignified and beautiful; as precious as the garments of royalty. Indeed, the Talmud informs us that when the wicked Persian king Ahasuerus made a feast for his advisors and officers and sought to impress them with his greatness (as recorded in the scroll of Esther, which tells the story of Purim) he put off his own royal vestments and donned the uniform of the High Priest…which was more precious than his own. These priestly garments were in his possession since the First Temple had been destroyed by the Babylonians. ...

The Garments Possess An Intrinsic Holiness

No priest, neither lay nor the High Priest himself, is fit to serve in the Temple unless he is wearing the sacred garments. As the Talmud states, “While they are clothed in the priestly garments, they are clothed in the priesthood; but when they are not wearing the garments, the priesthood is not upon them” (BT Zevachim 17:B). Conducting the service without these garments would render the priests the same as those who are not descendants of Aaron—all of whom are unfit for service in the Temple. ...

Actually, the Hebrew expression which we are translating as “sacred” or “holy” garments also means “garments of the Temple;” that is, the garments themselves show that their wearers are standing in the Divine service.

See rest of the article at (http://www.lttn.org/R5_Article2_TemplePriestlyGarments.htm)