The painting depicts the Sphinx triumphs over Oedipus at the crossroads on his journey between Thebes and Delphi. The Sphinx may be seen as a form of femme fatale, a common theme in Symbolist painting.
Opening poem of Buch der Leider by Heinrich Heine:
Nightly I see you in dreams-you speak,
With kindliness sincerest,
I throw myself, weeping aloud and weak
At your sweet feet, my dearest.
You look at me with wistful woe,
And shake your golden curls;
And stealing from your eyes there flow
The teardrops like to pearls.
You breathe in my ear a secret word,
A garland of cypress for token.
I wake; it is gone; the dream is blurred,
And forgotten the word that was spoken.