In this week's Parsha, Hashem commands Bnai Yisrael not to ever remove the poles from the rings which were attached to the sides of the Aron (שמות כ"ה:ט"ו). The Sefer HaChinuch explains that the purpose of this Mitzvah was to provide a safeguard so that the Aron would always be ready to travel, and so that it would never fall while being carried. The Chizkuni agrees with this, but adds that those poles could be kept on all year round, for the Aron was approached only once a year (on Yom Kippur), and the poles would thus never be in anyone's way. However, the copper altar, for example, had its poles removed to prevent accidents, because people were constantly in the courtyard where the copper altar stood. These explanations offer physical reasons as to why we have this Mitzvah.
Many understand this prohibition, however, as having a much more complex message. The Meiri claims that while the poles symbolize the ordinary, everyday chores of life, the Aron symbolizes the spiritual and holy; the combination teaches that we should have an element of Kedushah in everything we do in our daily lives. The Kli Yakar equates the poles to Bnai Yisrael, and the Aron to Hashem, showing how we must never stray from Hashem and His Mitzvos. Rav Shimshon Rafael Hirsch elaborates on the Chinuch's idea of the Aron always being ready for travel with a much deeper thought. He explains that the Shulchan, the Mizbeiach, and the Menorah, which did not have poles, symbolized Bnai Yisrael, leading free and comfortable spiritual and personal lives, undisturbed in their own land; this could happen only in Eretz Yisrael. These items thus had no poles. The Aron, on the other hand, reflects the essence of the Torah, which can travel throughout the world, hence the poles, symbolizing mobility. Lastly, the Netziv expresses a similar idea, saying that regarding the outer Mizbeiach and the Aron, the Torah relates the placing of the poles in the rings, but regarding the inner Mizbeiach and the Shulchan, we are told only of the making of the poles. This is because the former represent Tefillah, Avodas Hashem, and Limud Torah, which can be done anywhere, while the latter represent Malchus, royalty, and Kehunah, which are fully relevant only in Eretz Yisrael.
While this Mitzvah of leaving the poles inside the rings of the Aron may seem to be a simple Mitzvah at first glance, we now see that this is not so. Many important and fundamental ideas relating to Avodas Hashem can be learned from this "simple" Mitzvah. This truly proves the well known saying שבעים פנים לתורה, meaning there are many meanings that to be found in every detail of the Torah. We should always examine everything in the Torah fully, and see what we can learn from each Mitzvah.