You put together machines and water, and you get landscapes that look like this. And then you get sales that look like this. It's brute force. So what you've been doing in agriculture is you start out with something that's a reasonably natural system. You start taming that natural system. You put a lot of force behind that natural system. You put a whole bunch of pesticides and herbicides --  -- behind that natural system, and you
运用机械及水，得到了 现在这样一幅图景。然后这样的一些 产品就能够销售出去。这是巨大外力的作用。 这样一个发展农业的过程，是从 一个原本相当自然的体系起步， 最终去驯服这个自然体系。 你把很多外力施加于这个自然体系。 你使用了大量的杀虫剂和除草剂 在这个自然系统中。