Blavatsky traveled all over the world. She had a strange habit: she would carry a handbag in which she kept flower seeds; and wherever she went, whether by train or by car, she was throwing the seeds out on either side. People asked her why she was doing this. She said, "It is time for the rainy season; the water will fall on the seeds and they will sprout and grow into plants. Flowers will come. It will be very beautiful."
People said that even if the flowers blossomed, what did it matter to her? -- she was not going to pass along the same road again. She said, "I see flowers all around which have grown from seeds thrown by others and I am delighted. I owe a debt to those who sowed those seeds. By throwing these seeds I am paying back the debt. I imagine that others who pass by this road some time will be delighted, even though I may not pass here again. Even in my imagination I feel delighted at that happy prospect and I feel overwhelmed."
Have you ever imagined somebody being delighted because of something done by you? Even if you can understand by imagining it that somebody may be delighted because of you, or that somebody's heart may glow because of you, that is enough.