From http://www.reformjudaism.org/dust-and-ashes-and-holy

As Reb Bunam taught, it was necessary for the priest to be reminded constantly of the paradox of his position. Imagine how the two lapis stones and the breastpiece would weigh on his chest throughout the day, reminding him that his holiness was drawn from the God for whom he was ordained, and also from the people whom he was ordained to serve.

As he donned his sacral vestments, he was to be reminded of the holy nature of his position, but also constantly grounded as “from among the Israelites” (Numbers 3:12).

Earlier in Exodus 19:6, the Israelites are told that God expects them to be “a kingdom of priests and a holy nation.” Even though we, as Israelites, no longer wear the sacral vestments of the biblical priesthood, each of us must also be reminded that we are asked to live in service to God, and in service to each other. How would we live our days differently if we had affixed to our foreheads the words, “Holy to the Eternal”? How would we live differently if we had emblazoned on our shoulders and across our hearts the names of our fellow Israelites?

We must always be reminded that while we are only dust and ashes, we must shoulder the responsibility for a world that was created for our sake.