Fuseli here portrays the Three Witches from Shakespeare’s 1606 play Macbeth. As a literary device the Three Witches seem to be an inverted portrayal of the three white-robed Fates from Greek mythology, famous for assigning destinies to people at birth. The Three Witches lead Macbeth to his downfall.
This scene is painted straight from Macbeth (1.3.39-47):
. . . What are these,
So wither’d and so wild in their attire,
That look not like th’ inhabitants o’ the earth,
And yet are on’t? Live you? or are you aught
That man may question? You seem to understand me,
By each at once her choppy finger laying
Upon her skinny lips: you should be women,
And yet your beards forbid me to interpret
That you are so.