  The sub-parsec masing disk recently found to be orbiting a central mass of
$\sim3.6\times10^7$~\msun\ in the Seyfert/LINER galaxy NGC~4258 provides the
most compelling evidence to date for the existence of a massive black hole in
the nucleus of a galaxy. The disk is oriented nearly edge-on %($\bf i=83$\deg)
and the X-ray spectrum %(Makishima \etal\ 1994) is heavily absorbed. Therefore,
in this galaxy, the optical emission-line spectrum generally exhibited by an
active galactic nucleus is perhaps best sought using polarized light: probing
for light scattered off material surrounding the central source. New
polarimetry of NGC~4258 has uncovered a compact polarized nucleus whose
spectrum consists of a faint blue continuum similar to those of unobscured
quasars ($F_\nu\propto\nu^{-1.1}$), plus broadened (\twid1000\kms) emission
lines. The lines are strongly linearly polarized ($5-10$\%) at a position angle
(85\deg$\pm$2\deg) coincident with the plane of the maser disk. This result
provides substantiating evidence for a weakly active central engine in NGC~4258
and for the existence of obscuring, orbiting tori which impart many of the
perceived distinctions between various types of active galaxy.
