A traditional Buddhist and Hindu story.
Far, far away, in the abode of the great god Indra, king of heaven, hangs a wondrous vast net, much like a spider's web in intricacy and loveliness. It stretches out indefinitely in all directions. At each node, or crossing point, of the net hangs a single glittering jewel. Since the net itself is infinite in dimension, the jewels are infinite in number. The sparkling jewels hang there, suspended in and supported by the net, glittering like stars, dazzling to behold.
Close your eyes, now, and imagine what this magnificent jeweled net looks like, spread across the vast expanse of space. Now, keep your eyes closed and move in close to one jewel in the net. Look closely, and you will see that the polished surface of the gem reflects all the other jewels in the net, infinite in number, just as two mirrors placed opposite each other reflect an image ad infinitum. Each jewel reflected in this gem you are gazing into also reflects all the other jewels, so that the process of reflection is itself infinite.
Now open your eyes, and know that you are a sparkling jewel in Indra's Net, as is every person around you. Every jewel is connected with all the other jewels in the net; every person is intimately connected with all the other persons in the universe. Each has an independent place within the net and we all reflect and influence each other. A change in one jewel—or person—produces a change, however slight, in every other. Realize, too, that the infinite reflections speak to the illusory nature of appearances. Appearances are not, in fact, reality, but only a reflection; the true nature of a thing is not to be captured in its appearance. However powerful that appearance might be, it is yet only a reflection of what is real.
In addition, whatever you do to one jewel affects the entire net, as well as yourself. You cannot damage one strand of a spider web without injuring the entire web, and you cannot damage one strand of the web that is the universe without injuring all others in it, whether that injury is known or unknown to them. This can work for good or ill because, of course, just as destructive acts affect the entire net, so do loving, constructive, compassionate acts affect the entire net. A single helpful act—even a simple act of kindness—will send positive ripples across the infinite net, touching every jewel, every person in existence.