  Two sources of strong phases in the decays $B$ to $\pi\pi$ are identified:
(1) "quasi-elastic scattering" corresponding to intermediate states like
$\pi\pi$ and $\rho\rho$, (2) ``$c\bar{c}$'' corresponding to intermediate
states like $D\bar{D}$ and $D^{*}\bar{D}^{*}$. Possibilities of using data to
identify these two sources are discussed and illustrated. Present data suggests
both sources may be significant.
