I recently came across this quote from a Mary Oliver poem (in the image below), and I immediately felt that it really captures something true about the gesture behind Ash Wednesday, and the season of Lent, generally.
Remember that you are dust, and to dust you shall return.
As Christians, we are both of this world, and not. We are both beholden to our mortality, and not. In other words, we should love our lives while we are here, but just the right amount—not too much—for we are called to love the lives of others even more than our own, and we are destined for something greater still in our lives to come.
Transcription: For years and years I struggled just to love my life. And then the butterfly rose, weightless, in the wind. “Don’t love your life too much,” it said, and vanished into the world.—Mary Oliver