  This talk discusses our old work on the hadronic light-by-light contribution
to the muon anomalous magnetic moment and some more recent contributions. I
discuss the various contributions starting with pseudo-scalar meson exchange,
the quark- and pion-loop, as well as scalar and $a_1$-exchange. For the
$\pi^0$-exchange I point out a possible large enhancement when only connected
contributions are included. For the quark-loop I include some comments about
the more recent estimates of this contribution. The pion-loop is discussed in
more detail, in particular I discuss our unpublished work on including effects
from $a_1$ and the polarizability.
