There is no Mitzvah more rational and just than the Mitzvah to honor parents and to treat them with reverence (Maharal,Tiferes Yisrael §41). As Sefer HaChinuch explains, honoring parents is a matter of basic gratitude for their bringing him into this world and raising him. We may add that since people eventually become elderly and incapable of caring for themselves, the obligation of children to care for their parents is a vital societal arrangement.

Since this Mitzvah is logical, one would think that the Torah does not have to mention it; yet, the Torah mentions it multiple times and places great emphasis on it. Sometime between the Exodus and the Giving of the Torah, when the Jewish people arrived at Marah, Hashem decided that the Jewish people could not go any longer without Torah study, and He commanded them regarding three Mitzvos; this Mitzvah was one of them. Then, at the Giving of the Torah, Hashem placed this Mitzvah on the first of the two Luchos, among the Commandments that pertain to His own honor. Although His words in the Ten Commandments were concise and few, He promised great reward for fulfilling this Mitzvah — which is basic human nature, after all! The extent to which the Torah obligates a person to honor his parents is mind-boggling: a person is required to accord his parents the honor due to a king and queen (Pirkei D’Rabbi Eliezer §39), and indeed, to honor them like the King of the world Himself (Ramban)! Clearly, this Mitzvah is more than just a reminder to act morally.

We may understand this based on what Sefer Hachinuch writes, that by honoring one’s parents, he comes to realize that he ought to show even greater appreciation for the Creator, the ultimate source of any benefits he has ever received, both from his parents and other intermediaries. Had Hashem not created each person with parents and commanded him to honor them, he would have had difficulty understanding his more abstract debt of appreciation to the invisible Hashem. This Mitzvah is therefore a stepping stone to all the Mitzvos. Thus, when Mesillas Yesharim defines the Mitzvah of loving Hashem, he writes, “We are commanded to instill in our hearts love for Hashem, such that we feel a desire to bring Him pleasure, just like a person feels a desire to bring pleasure to his parents.” Since how a person treats his parents affects how he treats Hashem, the honor due to them parallels the honor due to Hashem.

The Sages state further that when a person honors his parents, Hashem dwells among them and considers it as if He has been honored (Kiddushin 30b). In other words, honoring parents does not just lead to honoring Hashem; it is honoring Hashem. In their role as a person’s forebears and the providers of all of his needs, parents represent Hashem, and their honor is Hashem’s honor. Thus, as the Gemara there relates (ibid., 31b), when Rav Yosef heard his mother approaching, he would immediately stand up, saying, “The Divine Presence is approaching!”

With this understanding, we can comprehend the extent to which the Torah obligates us to honor our parents. The Zohar (Pinchas pg. 215) writes that one must honor his parents “like a horse and like a donkey,” running to fulfill their every request even if it entails demeaning oneself like a lowly animal. Rabban Shimon ben Gamliel, who excelled in honoring his illustrious father his whole life, acknowledged that Eisav outdid him a hundredfold (Bereishis Rabbah 65:16). It seems that there is no limit to the Torah’s obligation to honor parents — just like there is no limit to that amount due to Hashem. The obligation to honor parents is so great that it is impossible to fulfill it completely, and only someone who never knew his parents cannot be held accountable for treating them with insufficient honor. Thus, one of the Sages remarked (Kiddushin 31b), “Fortunate is he who never knew his parents (i.e., an orphan from infancy)!”

Abarbanel adds that honoring parents is an essential component of the Torah’s continuation from generation to generation, for only if children honor their parents will they be willing to accept from them the traditions of the Torah. Accordingly, Rav Tzaddok of Lublin explains that Rav Yosef associated his mother's footsteps with the approach of the Divine Presence because she had educated him in the Torah’s ways, and he thus regarded her as a representative of Hashem (Pri Tzaddik, Chayei Sarah §2).

In conclusion, honoring parents is not merely a moral obligation that we share with all the nations; it is a Divinely given Mitzvah that connects man on earth to his Creator in Heaven. However, being a moral obligation in its essence, it makes our perception of the parallel honor due to our Father in Heaven natural, and this permeates and inspires every aspect of our relationship with Him.

Eisav, who is remembered for excelling in this most difficult Mitzvah but failing dismally in all other Mitzvos, apparently did not realize this distinction. The honor he accorded his father did not bring him to honor Hashem similarly. We do not even find that he honored his mother, and some infer from this that the honor he accorded his father was not for the sake of the Mitzvah, but rather for hope of gain. Be that as it may, he merited greatness in this world for this single Mitzvah (Bereishis Rabbah 82:14). If we fulfill this Mitzvah as a fundamental part of our service to our Father in Heaven, we can expect a far greater reward. Tanna D’vei Eliyahu (§24) sums it up: Whoever desires wealth, honor, and life in this world and the World to Come should do the will of his Father in Heaven and honor his father and mother.