"And yet i would not sleep; merciful powers, restrain in me the cursèd thoughts that nature gives way to in repose" (2.1.7-9). This is Banquo complaining about his inability to sleep as a result of nightmares. This picture is an open eye, representing the inability to sleep because of what's inside the mind (depicted in the person within in the eye in this photo)
Though out story, as Celia and Marco battle against each other with their allusions and their manipulations they fall in love, only to find out that one of them have to die in order to end it. Celia, knowing of a way out, removes them from the physical world.