"Look In Thy Heart And Write"

Context: Sir Philip Sidney, in the courtly tradition, writes a sonnet sequence to win the favor of a lady whom he admires, generally thought to be Penelope Devereaux. The poet, searching for words to express his love, studies poetry, vainly reading the verse of others as he strives to write, but his words falter without "Invention," (creative imagination) until the poet "great with child to speak," gives literary birth to his sonnets by following the advice of his Poetic Muse, which tells him to "look in thy heart and write:"

But words come halting forth, wanting Invention's stay;
Invention, Nature's child, fled step-dame Study's blows;
And others' feet still seemed but strangers in my way.
Thus great with child to speak, and helpless in my throes,
Biting my truant pen, beating myself for spite:
"Fool!" said my Muse to me, "look in thy heart, and write."