You do yourself no good repeating the quote. I said I agree with it. But Trickle Down Theories do not just assume this. They try to look, as Jim says above, to the good in humanity to do something right. They don't just assume it.
The problem is that humanity is greedy, just as I said above. Especially when you get to bigger and bigger groups looking out for themselves. The bottom line of a company is...the bottom line. Let's not forget what many companies do in the way of charitable giving...not that it's enough, but they do.
You know, the best way to take care of the poor is for each of us to directly do it. In the Philippines, where there is no such thing as welfare, poor people with a one room cardboard hut will allow someone with less to sleep next to them on the dirt. Out of gratitude, the next morning, the poorer one will sweep out the hut. Trickle down works in the Bible, too. Remember the widow who gave her two mites. How'd she get them? What'd she do with them?
The pope is advocating that people, in general, be less greedy. He's not just shaking his fist at corporations. I'm sure if you thought about it, you could find a way to be more generous. I know I can. And that's the point.