After reading Tolstoy's "The Forged Coupon" I drew a diagram of events and effects.
But then I found another, and better, one. Why not steal it? So here it is:
1 thing leads to another. Evil begets evil. As written on the back cover of my Penguin copy The Death of Ivan Ilyich and Other Stories, the story "shows a seemingly minor offence that leads inexorably to ever more horrific crimes".
It would be simplistic, however, to say that "The Forged Coupon" is about how evil begets evil. Every single person in the story who does wrong makes a conscious choice to do wrong. These characters, when suffering a wrong, transfer the loss to someone else or seek revenge or develop a hatred against the whole world or get led astray, and they do so because they don't know they have a choice, because they think that's the way it should be. They may react in a different way, and don't. They may choose another path, and don't. It's unlike "Polikushka", in which the disaster is caused by chance, by external circumstances. If "The Forged Coupon" is more like a parable than a novella of the realist tradition, the moral is not only that one shouldn't commit even a minor offence (such as forging a coupon) because it may lead to a series of crimes, but also that one has reason and free will and under unfortunate circumstances can choose to be bad, like those characters in the story, or to be good. They only come to understand it in part 2 of the story. Despite the feeling of contrivance now and then, as this is a strongly didactic piece written in Tolstoy's last years, it is a very good story.