A good person will never die. Of course, they will breathe their last, or they'll be buried six feet under. But, according to the Persian poet Saadi, they will live on in the behaviour and the culture of those they leave behind. If you've ever been to a funeral or had a loved one die, you'll know that one of the most common sympathies people give is to say, 'They will always live on in your mind.' And it's true. You can relive your time together so long as the memories live in you.
But what Saadi is saying is something more. Saadi argues that, if you have a good person, that they will come to embody and represent certain models of goodness. For example, let's say that your grandmother was a kind and generous person. Every time you walked through her door, she would shower you with love and warm attention. Now, every time you show a similar generosity to other people today, you will bring a bit of your grandmother to the room, because your grandmother embodies kindness.
In Aztec philosophy, it was thought that, when a good person died, they would join the sky to carry on pushing the sun. In death, they provide warmth, light, and life to those who are still living. So too with goodness. If you are kind, loving, generous, brave, wise, or any virtue at all, you will bring more of that into the world. If you burn brightly, you will make the world bright, and the world will stay lighter for a long time after you have died.