There are in nature neither rewards nor punishments, there are consequences.
This gave me much to think about over the years. In my university studies in my major of Studies in Religion, I learned about the Buddhist doctrine of moral causation. I heard the Buddhist saying You may forget your actions but your actions don't forget you. I found the 'consequences' thinking a much more satisfactory view than much of the teaching I had heard on sin in the Christian tradition. Consequences spoke to personal responsibility, to fall out, outcomes. Consequences thinking was not a legalistic laundry list which could rule murder out and let hate in, keep the icons out of churches but let in the ambition of the world. And it was not inimical to Christian teaching. Such a view of consequences was a good companion to Jesus's teaching in Matthew 7:17
And where did this memorable quote come from? It came out of the 19th century from Robert Green Ingersoll - noted unbeliever and critic of religion. A new book reviewed here should bring his thought back into modern knowledge.