The following distinction between development and expansion, made by Amory Lovins of the Rocky Mountain Institute , is central to the idea of sustainable population."The assumption that economic prosperity requires growth seems so reasonable that most of us don't think much about it. After all, it's what we've always been told; politicians, business boosters, economists, and the media all seem to take it for granted. The assumption is so pervasive that virtually every American community is looking for ways to grow out of its economic problems, even when those problems are themselves the result of growth.The trouble is, the word "growth" has two fundamentally different meanings: "expansion" and "development." Expansion means getting bigger; development means getting better, which may or may not involve expansion. This is no mere semantic distinction. Many communities have wasted a lot of time and energy pursuing expansion because that's what they thought they needed, when what they really needed was development. To avoid confusion, let's define growth here only as getting bigger—expansion—and development as getting better."