In Sonnet 38, the speaker makes a distinction between his talent and his "Muse."
First Quatrain: “How can my Muse want subject to invent”
The speaker opens Sonnet 38 by addressing his talent, asking how his Muse could lack something worthy to write about as long as the speaker possesses such strong and capable talent. His talent resembles living waters that “pour[] into [his] verse / [their] own sweet argument.”
His own talent informs his verse with such sweetness and quality that is “too excellent / For every vulgar paper to rehearse.” His boasting merely elucidates the fact that his poems yield a high quality, not like lesser work with which inferior poems must struggle.
Second Quatrain: “O! give thyself the thanks, if aught in me”
The speaker then advises his talent (which also co-exists with the speaker’s very soul) to give credit to itself, if the poet/speaker has anything worthy to say. He reckons that when talent is present, anyone would be capable of writing: “For who’s so dumb that cannot write to thee, / When thou thyself dost give invention light?”
Because his strong talent sheds such a vigorous light of creation, the speaker cannot fail to produce worthy art that he is sure will endure down through the ages.
Third Quatrain: “Be thou the tenth Muse, ten times more in worth”
Many earlier poets have invoked the Muses when beginning a poem. Homer began The Iliad with “Sing, O goddess, the anger of Achilles son of Peleus,” and The Odyssey with “Tell me, O muse, of that ingenious hero.” Edmund Spenser begins The Faere Queene with “LO I the man, whose Muse whilome did maske.”
But this speaker invokes his talent to serve as the “tenth Muse,” which he deems ten time more valuable than the other nine: “Be thou the tenth Muse, ten times more in worth / Than those old nine which rimers invocate.” This poet is more than a rimer; he is indeed a true poet.
The poet who calls on his own soul/talent will produce works even greater then these earlier poets who relied upon the nine Muses. At least, this speaker has confidence that his own talent is up to this task.
The Couplet
The speaker then becomes more humble by asserting that if his “slight Muse” can create poetry that is pleasant for his own enigmatic times, he himself may incur the pain of the arduous labor, but his talent/soul will receive “the praise.”
He acknowledges that his mind and ability apart from his poetic talent are small and must put forth great effort, but his talent is able to shine through his mental dullness to hoist his creations to greatness.
Other articles on Shakespeare: Who is Shakespeare?
Sonnet Commentaries: Sonnet 1, Sonnet 2, Sonnet 3, Sonnet 4, Sonnet 5, Sonnet 6, Sonnet 7, Sonnet 8, Sonnet 9, Sonnet 10, Sonnet 11, Sonnet 12, Sonnet 13, Sonnet 14, Sonnet 15, Sonnet 16, Sonnet 17, Sonnet 18, Sonnet 19, Sonnet 20, Sonnet 21, Sonnet 22, Sonnet 23, Sonnet 24, Sonnet 25, Sonnet 26, Sonnet 27, Sonnet 28, Sonnet 29, Sonnet 30, Sonnet 31, Sonnet 32, Sonnet 33, Sonnet 34, Sonnet 35, Sonnet 36, Sonnet 37, Sonnet 73, Sonnet 96, Sonnet 116, Sonnet 126, Sonnet 130, Sonnet 138
