Our body and mental age.
We are getting old - physically decaying. Yet we think we are still young. Inside, we're just the same age as we used to be, it's just that our bodies are out of synch with our age. We have in our mind an image of when we were young. Our spirits are as young as the date printed on the old photos of ourselves, although the photos are fading into black and white memories. Yet they never disappear.