And there you shall build an altar to the Lord you G‑d, an altar of stones: you shall not lift up an iron tool upon them (27:5)

Iron was created to shorten the life of man, and the altar was created to lengthen the life of man. It is therefore not fitting that the shortener shall be lifted upon the lengthener.

The Talmud, Midos 3:4

Its [the Torah's] way are ways of pleasantness, and all its paths are peace.

Proverbs 3:17

Rabbi Schneur Zalman of Liadi once received a silver snuffbox as gift. But the Rebbe did not want to put it to its intended use, and remarked: "There is one part of the body which is not constantly seeking gratification - the nose. Should I train it, too, to be a pleasure-seeker?"

Instead, Rabbi Schneur Zalman found a more lofty use for the gift: he detached the snuffbox's cover and used it as a mirror to help him center the teffilinon his head.

This incident was once related to Rabbi Schneur Zalman's grandson, Rabbi Menachem Mendel of Lubavitch. As the one telling the anecdote described how Rabbi Schneur Zalman "broke off" the cover of the snuffbox, Rabbi Menachem Mendel remarked: "No, no, my grandfather never broke anyone or thing. He merely removed the hinge-pin which connected the upper part to the lower."

Said the Lubavitcher Rebbe shlitah:

The deeper significance of Rabbi Menachem Mendel's clarification is this: Rabbi Schneur Zalman would never have "broken off" the cover. True, his entire life was devoted to sublimating the ordinary and elevating the mundane. But he taught that the way to deal with the material world is not to repress or crush it, but to gently detach the upper from the lower: to extract, by harmonious and peaceful means, its lofty potential from its lowly enmeshments.