What lessons do we learn from the poem "Fable" by Janos Pilinszky? Discuss using evidence from the poem.

There are a lot of ways to interpret this poem, which means that there are several, potentially conflicting, ”lessons” the poem might teach.
One way to understand the poem is that the wolf is misunderstood. The poem is about the wolf in that we see and feel what the wolf sees and feels. The wolf craves shelter and does not mean to harm anyone. However, because he is a wolf, he is killed when discovered in the morning. The lesson would be that although one may look "bad," one may not actually be bad.
Alternatively, you could think about the poem‘s point of view as ironic. The voice that tells us that the wolf is a “child-like beast” might not be serious, and the reader might be meant to question the wolf’s real motive, which perhaps is to claim the house for himself. In this case, the people are right to kill the wolf because wolves really are bad, no matter how nice they seem.
If you think about the poem as a “fable” about war, World War II in particular, than the lesson might be about how want makes beasts of us all. In this reading, the house is essential to survival; the humans have it, and the wolf does not. Even though the wolf does not attack the humans directly, they still kill the wolf since he represents a threat to their survival. In short, they do not want to share.
Another lesson might be that even though someone might seem evil or might be our enemy, it is still possible to empathize with them. The poet clearly does empathize with the wolf (that is, if we believe what the poet says)—the wolf is “lonelier than the angels” and is described as “child-like”; he finds the people in the house “beautiful.” There is a sense of resignation in the wolf’s decision to enter the house, stop “in the middle of the room,” and “never move from there more.” It may be that the wolf is childlike in that he does not understand that others see him as merely a wolf. Additionally, his weariness with life (or the war) has outweighed whatever forces kept him apart from others. He loves the house because it represents rest, something he craves regardless of its cost.