A phantom is that to which we are brought by such a fanciful and vain attraction; this is to be seen in melancholy and distracted persons.

Of this sort was Orestes in the tragedy, pronouncing these words: Mother, these maids with horror me affright; Oh bring them not, I pray, into my sight! They're smeared with blood, and cruel, dragon-like, Skipping about with deadly fury strike.
These rave as frantic persons, they see nothing, and yet imagine they see.

Thence Electra thus returns to him: O wretched man, securely sleep in bed; Nothing thou seest, thy fancy's vainly led.
(Euripides, "Orestes", 255.) After the same manner Theoclymenus in Homer..