When I was a child back in the 40s, we had no air conditioner, so the summer nights were sometimes hot, sticky and unbearable. We lived in a flat in my grandparents house which had a large front porch. After dinner and the dishes were done, my entire family would get together on the porch for the evening and try to keep cool. Sometimes my cousins and I would even sleep outside on that porch and that's where I would wait for the sound of the leaves. It didn't take much, but a slight breeze through those leathery deep green leaves would produce a sound I can't forget. I was visiting a friend's farm in Wisconsin and again, sitting on their front porch at night I could hear the rustle of those cottonwoods which I recognized immediately. What a great memory.