The relation between the masses and mixing angle in a nonet of mesons is studied in a simple quark-gluon picture. We find that both the splitting of ${{\ensuremath{\mu}}_{\ensuremath{\eta}}}^{2}$ from ${{\ensuremath{\mu}}_{\ensuremath{\pi}}}^{2}$ and the departure of ${\ensuremath{\theta}}_{P}$ from ${\ensuremath{\theta}}_{\mathrm{ideal}}$ are due to annihilation forces. Mass formulas which describe the masses in a nonet in terms of two parameters are derived and found to be in good agreement with observed masses for the ${0}^{\ensuremath{-}+}$, ${1}^{\ensuremath{-}\ensuremath{-}}$, and ${2}^{++}$ nonets.