The Torah prohibits approaching the altar by steps: "And you shall not go up with steps to My altar, so that your nakedness not be revealed upon it" (Exodus 20:23). From this verse, the rabbis derived that the altar must be accessed by a ramp rather than stairs. When a priest walks up steps, his legs separate with each stride, potentially exposing what should remain covered. A ramp allows a smooth, gliding ascent.
But the Mekhilta noticed a gap. The verse explicitly mentions ascending — going up. What about coming back down? When a priest descends steps, the same exposure problem exists. Must a ramp be used for the descent as well?
The answer comes from the reason given in the verse itself: "so that your nakedness not be revealed." The operative principle is not about the direction of movement but about covering. Whether ascending or descending, the concern is the same — maintaining the dignity of the priest before the altar. Since the problem of exposed nakedness applies equally to going up and coming down, the ramp requirement applies in both directions.
This teaching demonstrates a classic Mekhilta technique: identifying the underlying reason behind a commandment and extending its application beyond the specific case mentioned. The Torah spoke of ascending because that is the more obvious scenario. But the rabbis recognized that the real issue was dignity, not direction — and dignity has no directional preference.