‘Kindly mother of the twin Cupids, favour me!’ I said.
She glanced back towards her poet: ‘Why do you
Need me?’ she said. ‘Surely, you sing greater themes.
Have you some old wound lingering in your heart?’
‘Goddess, ‘ I replied, ‘you know my wound.’ She laughed,
And the sky immediately cleared in her direction.
The opening to Ovid's Fasti IV (translated by A S Kline, 2004: his whole version of the poem is well worth checking out). My favourite, and my most applicable, invocation of the Muse.