Paper moves ideas. To pass along a sheet of paper is to pass along the ideas written on it. Paper preserves ideas. If you give a speech, you will only be heard today. If you give a sheet of paper, you may be heard for years by people you've never seen.
Copiers reproduce ideas.
Copiers turn ideas into something like living things, with no limit to their growth. Copiers are genital organs of ideas. Suppose an activist issues 100 copies of a paper. Then these 10 will issue 1,000 copies among them. This spectacular growth is the work of the chain letter principle.