  To illustrate the campaign to extend our knowledge of the charmonium
spectrum, I focus on a puzzling new state, $X(3872) \to \pi^+\pi^- J/\psi$.
Studying the influence of open-charm channels on charmonium properties leads us
to propose a new charmonium spectroscopy: additional discrete charmonium levels
that can be discovered as narrow resonances of charmed and anticharmed mesons.
I call attention to open issues for theory and experiment.
