When Moses approaches the burning bush, G-d instructs him to remove his sandals because he stands upon “holy ground.” (Exodus 3:5). But G-d doesn’t explain why Moses shouldn’t wear sandals upon holy ground. Why not, for example, just prostrate himself, kiss the ground, erect an altar, sacrifice a ram, or do something else? Why remove his sandals?
In his Reform Chumash commentary, Rabbi Gunther Plaut comments: “Many explanations have been offered for the custom of removing one’s footwear when entering a sacred place (practiced in various cultures, for instance, Moslem and Japanese) one enters the presence of divinity as clean as possible; one lowers his status in a gesture of self-abnegation; one unties all knots when coming before G-d. Joshua, too, when meeting a divine apparition, is bidden to remove his sandals, and the priests followed this custom when entering the Temple Mount.”
A Chasidic explanation is that G-d was telling Moses to: “Remove the shell of habit that encloses you, that keeps you from your immediate experience, and you will recognize that the place on which you happen to be standing at this moment is holy ground. For there is no rung of being on which we cannot find the holiness of G-d everywhere and at all times.”
According to Halachah (Jewish law), Kohanim remove their shoes before blessing the congregation (“duchaning”) because they usually stand on a platform (duchan). Explanations include acknowledging G-d as the source of all blessings, respect for the congregation, and protection of the priest’s reputation.
Without disagreeing with any of these, I’d like to suggest an explanation for G-d's instruction to Moses that relates specially to removing his sandals -- and that is relevant to our behavior. Toddlers must do so before entering indoor public play areas. While cleanliness might be one reason, I suspect that the principal one is so they won’t hurt each other while climbing over each other. They haven't yet learned self-restraint or adequate consideration for others, so we must remove their "weapons."
As with physicians, the first rule we impose upon their arena of interaction is: “Do no harm.” (As a lawyer, I might say that the first rule is actually: “Avoid lawsuits.” But this is simply an extension of “Do no harm,” as liability would be based upon negligence, i.e., failure to take appropriate care to avoid harm.)
What made the ground upon which Moses trod “holy?” Perhaps it was not G-d’s presence but rather the burning bush! It gave light and heat, yet its flames neither consumed it nor spread; it did no harm.
Doing no harm is the true essence of proper conduct, i.e., holiness. This would be consistent with Hillel’s maxim: “What is hateful to you, do not do to others; this is the entire Torah, now go and study (the details, to learn how to apply this great principle in every aspect of your life).”
G-d, through G-d’s Torah placed in our hands by Moses, commands us to “Be Holy.” G-d was telling Moses to remove his sandals because they represent harm as we walk -- and tread upon others -- through life. Our principal guide in fulfilling this mitzvah should be to “Do no harm.” In this regard, we should consider our every interaction with others to be "walking upon holy ground.”
Kee mi’tzion taytzay Torah, u’dvar H” mi’Yerushaluyim! For the Law will go forth from Zion, the word of G-d from Jerusalem. (Isaiah 2:3)
Shabbat Shalom from the Holy City!
(For more information about the Birkat Kohanim custom of removing shoes, see: http://halachipedia.com/index.php?title=Birkat_Cohanim#cite_note-18; http://vbm-torah.org/archive/tefila/14tefila.htm; http://ph.yhb.org.il/en/03-20-08)