> Rivers Rivers are doubtless cleaner than they were 400 years ago, too; it's enormously valuable that we can now treat human waste properly. Dunghills, refere

> Rivers Rivers are doubtless cleaner than they were 400 years ago, too; it's enormously valuable that we can now treat human waste properly. Dunghills, referenced all the time in historic texts (like Luther's "snow on a dunghill" image), were literal piles of human feces. Imagine where they went when it rained, and remember how a lot of waste was just dumped onto streets, into water, and so on; 50 million people dumping raw sewage into rivers or storing it in heaps, will pollute the environment much more severely than 1 billion people with plumbing, running water, and centralized sewage-treatment plants.