In the last decade of his life, poet William Carlos Williams, went on to write some of the greatest poetry of his career. In one of those poems he writes, "The descent beckons as the ascent beckoned." Something important about Zen practice really only comes into its own in the second half of life, as "the descent beckons." Zazen when you're young teaches you there are things you can do you never thought you could. Zazen as you get older teaches you there are things you can't do that you always imagined you'd be able to do forever. The latter is where we see what we learned in our early years of practice. Can we suffer without self-reproach? Without thinking it's a sign we've screwed it all up? Can we allow ourselves to be vulnerable and human? Ultimately, we don't know what unexpected worlds await us when the world we've been pursuing is lost.