This painting is dealing with self confidence and the power of character.
Normally Spinx described in the Greek mythology as a powerful and wise being partly woman, partly bird and partly a lion.
But this spinx figure has no lion elements, it's more of a woman-swan being that surly has no real physical/external power. And yet it projects power and confidence that actually comes from its inner power of character - the true power human can posses.
But is this inner power real or merely a mask?