Who is Sophocles in the poem "Dover Beach"?

Historically, Sophocles was a great playwright in Athens in ancient times. His most famous play was Oedipus the King. One of his major contributions and innovations in the dramatic world was the introduction of a third actor into a performance. In the poem "Dover Beach," Sophocles functions as a historical reference and a character of sorts. The narrator of the poem is speaking to his beloved, and stanza two sees the speaker of the poem bringing in Sophocles as a historical reference to the suffering and sadness of the world introduced in stanza one. Sophocles acts as a link between stanza one and two because he is linked to the mind of the poem's speaker. The poem's narrator listens to the sea and the "grating roar" it makes upon rocks, and that sound is also the exact sound that Sophocles heard all those centuries ago.

Sophocles long ago
Heard it on the Ægean, and it brought
Into his mind the turbid ebb and flow
Of human misery;