What does the quote below mean from King Lear?
This quote occurs in a conversation between Albany and Goneril in King Lear. Basically, in this scene the Duke of Albany blasts Goneril for the evil she has committed against her father, King Lear. He characterizes the Goneril and Regan as "tigers, not daughters."
Albany is so upset by their misdeeds that he is convinced that heaven must send down their "visible spirits" (angels) to right the wrong, "these vile offenses" that have been done against the King. Albany believes if heaven does not take action to restore the balance between good and evil, then the result will be utter chaos, with humanity turning against itself "like monsters of the deep."
The dialogue, as noted above, is a part of an exchange in which the Duke of Albany is condemning the evil acts of his wife, which including plotting to kill him.
The theme of the speech is what is known as "theodicy" or divine justice. One question frequently asked in Christian settings is how it is that a divine, omniscient, omnipotent, and benevolent God could allow evil in the world. In this case, even more specifically, Albany wonders how evil can go unpunished, and why God has not sent angels to smite Goneril. He solves his own conundrum by suggesting that if God does not smite evil, then humans must do so, taking upon themselves the task of retribution, although he does wonder if this itself will put fallen humanity in a state of perpetual war and violence.