… and then the boy said, "Wait!" running towards the Alien, "take this, this is the cure for our Race's worst ailment, the cure for our planet's resources. Please, plant it on your planet in an area similar to Earth's atmosphere, give it love and help it survive. Use it for your people." The boy handed him a vial with three seeds in it and a separate container with a flower in it. "The flower is called Cannabis. This is the greatest gift I have to offer."
The Alien, took the gifts and walked away to his ship, then sped off into the sky. 70 years later, there was a knock at the now elderly man's house. Upon answering it, there stood the Alien. The Alien extended his hand and placed into the man's hands a container. "Thank you, Human for the seeds you once gave me. Here is a present from our planet to show our appreciation." The man opened the container, and inside was the most beautiful flower he had ever seen. "This is what we have perfected over the years with your help." The Alien bowed, then, left.
The man smoked the flower, and with a small breath, his body rippled, de-aging his body to new youth. He opened his eyes, and looked in the mirror, his body had a glow of perfection to it, as he was 50 years younger again.