The beginning of the parsha discusses the laws pertaining to a Jewish slave. Although one can only be sold into slavery for the duration of a single shemittah cycle, should one wish, he can extend his stay in his master's house until yovel. However, he must first have his ear pierced by beis din. As the Torah tells us, "His master shall bring him to the Elohim, and shall bring him to the door or doorpost and his master shall bore through his ear with an awl and he shall serve him forever (i.e. until yovel)" (Shemos 21:6). Rashi tells us that "Elohim" mentioned in this pasuk refers to beis din.
Why does the Torah use the name of Hashem to refer to beis din? The Ramban explains that Hashem can be found with the beis din during all their legal proceedings, and it is He Who acquits and it is He Who convicts; for He is the ultimate Judge. In other words, the Shechina rests upon the judges and the actual judgment emanates from Him.
Rav Wolbe (Shiurei Chumash, Mishpatim 21:6) cites the Rambam's explanation of semicha (Hilchos Sanhedrin 4:1) to shed light on understanding the root of this phenomenon. "Moshe placed his hands upon Yehoshua, and likewise Moshe placed his hands upon the seventy elders and the Shechina rested upon them. Those elders placed their hands upon others, and these others placed their hands upon others. Consequently, anyone who received semicha can trace himself back to the beis din of Yehoshua and Moshe Rabbeinu." Why did the Rambam feel it pertinent to add that after receiving semicha the Shechina rested upon them? He was informing us that by means of semicha, the elders of the generation have the ability, so to speak, to give over the Shechina to the next generation!
We find a similar idea in the yotzer recited during Shacharis. We proclaim that all the angels accept the yoke of heaven from one another. The Gra explains that each angel accepts the yoke from an angel greater than he. The ability for the Shechina to rest upon both the angels and the judges is dependent on their accepting the yoke of heaven from one greater than they. We might add, says Rav Wolbe (Alei Shur vol. I, p. 75), that the same idea applies to the disciples of a Rebbi. It is not enough for them to merely accept upon themselves the yoke of heaven; they must accept it from someone greater than them. By accepting the yoke from one's Rebbi, he becomes a link in the chain of transmission of the Torah. This enables a person to receive the Torah in its truest form, for this link connects him back to Moshe Rabbeinu who received the Torah from the hand of Hashem.
Accordingly, we can appreciate the importance of connecting to a Rebbi. One must find a Rebbi from whom he can gain in Torah and avodas Hashem. Although this is the first step in spiritual growth, it also takes a certain level of maturity and pursuit of truth. One must be willing to rescind his own position should his Rebbi disagree, and he must be willing to accept criticism should the Rebbi feel it appropriate. As we all travel down the road of life, we would be completely lost without the direction of a spiritual GPS. Our GPS is our Rebbeim, who not only guide and direct us, but also connect us back to Moshe Rabbeinu who received the Torah from Hashem Himself!