T'tzaveh -- Exodus 27:20 - 30:10

(36) You shall make a frontlet of pure gold and engrave on it the seal inscription: “Holy to G-d.” (37) Suspend it on a cord of blue, so that it may remain on the headdress; it shall remain on the front of the headdress. (38) It shall be on Aaron’s forehead, that Aaron may take away any sin arising from the holy things that the Israelites consecrate, from any of their sacred donations; it shall be on his forehead at all times, to win acceptance for them before G-d.

(29) Aaron shall carry the names of the sons of Israel on the breastpiece of decision, on his heart, when he enters the sanctuary, for remembrance before G-d at all times.

"And these are the garments they shall make..." The eight garments [atone] for eight types of transgressions.

1. Ephod (apron) - idol worship עבודת גילולים

2. Michnasayim (linen breeches) - sexual impropriety

3. Katonet (tunic) - bloodshed שפיכות דמים

4. Choshen (breastplate) - errors in judging, since it's "Choshen Mishpat" -decision/law

5. Me'il (robe) - lashon ha ra (sin in speech)

6. Mitznefet (headdress) - arrogant spirit

7. Tzitz (frontlet) - cheekiness, stubborness

8. Avnet (sash) - inappropriate inner thoughts

(30) Inside the breastpiece of decision you shall place the Urim and Tummim, so that they are over Aaron’s heart when he comes before G-d. Thus Aaron shall carry the instrument of decision for the Israelites over his heart before G-d at all times.

את האורים ואת התומים; the Urim and the Tummim: the function was somewhat similar to that of oracles employed by the priests of idolatrous cults. If those had any value at all, -and we may assume that at least their worshippers had concluded that they did, -how much more influential would these urim ve-tumim in the sacred garments of the High Priest be in order to elicit answers to questions posed to G-d, seeing that the means employed were holy and sanctioned by G-d Himself?

(43) They [breast piece, ephod, robe, fringed tunic, frontlet, headdress, sash, breeches] shall be worn by Aaron and his sons when they enter the Tent of Meeting or when they approach the altar to officiate in the sanctuary, so that they do not incur punishment and die. It shall be a law for all time for him and for his offspring to come.

...the Urim and the Tummim were the holy Names of G-d, and it was by virtue of the power residing in these Names that the letters inscribed upon the stones of the breastplate would light up before the eyes of the priest who inquired of their judgment. For example, when they inquired, Who shall go up for us first against the Canaanites, to fight against them, the priest fixed his thoughts on those Divine Names which were the Urim [literally: “lights”], and the letters forming the name Yehudah lighted up before his eyes, and [for the word ya’aleh — “he shall go up”] the letter yod lighted up from the word Levi, the ayin from Shimon, the lamed from Levi, and the hei from Avraham which was also written there, according to the opinion of our Rabbis, or perhaps the hei from Yehudah lighted up a second time. Now when the letters lighted up before the eyes of the priest, he did not yet know their arrangement...But then there were other sacred Divine Names called Tummim [literally: “perfection”], through whose power the priest’s heart was made perfect to understand the meaning of the letters which lighted up before his eyes...