William Blake's allegorical poem, "A Poison Tree," is concerned with the subject of anger. The speaker of the poem reveals to his friend that he is angry, and the anger dissipates. But when the speaker hides his anger from his enemy, the anger grows, much like a tree. The fact that the tree is "poison" tells us that, by ignoring or suppressing anger, we are also poisoned. The apple that appears on the tree of anger symbolizes that poisonous effect. The final line is ominous; the speaker's delight at the "foe outstretched beneath the tree" offers a warning about what happens when we suppress our anger. If we ignore or deny our feelings, we will become wicked, bitter, and even vengeful.