Something worth appreciating is that one of the key motives for incorporating packages into CL were to avoid problems due to non-hygienic macro expansion, because they make the discipline of writing programs that avoid inadvertent capture much easier.<p>It's not quite true to say that packages are to Common Lisp what hygiene is to Scheme, but it is a large part of it. I'd like this paper a little bit more if it had said something about this, but the final thought that <i>Packages control how the reader maps strings onto symbols (and how PRINT maps symbols onto strings), nothing else.</i> is I think helps appreciate the point.