The themes of the poem "Crutches" by Bertolt Brecht is one of personal weakness (disbelief in self) and overcoming them.
In the poem, the man believes himself to be completely dependant on the crutches he uses to walk. While he can walk without them, his mental dependency has become one of physical dependency (in his mind).
Many times, it is simply ones mind which limits them from being able to do something. Here, this is precisely what Brecht is explaining. The breaking of the crutches by the physician shows the man that he can no longer be dependant upon his mental crutch. Therefore, the loss of the crutch enables the man to examine his disbelief in himself and, instead, force him to believe in his own strength.
Some of the main themes throughout the poem "Crutches" by Berthold Brecht examine self-reliance, confidence, and overcoming obstacles. As was mentioned in the previous post, the poem is about a person who has become mentally and physically dependent upon their crutches. After visiting a "great" physician who takes and breaks the crutches against his back, the speaker is forced to walk by himself. The speaker says that he is now cured and does not depend on the crutches any longer. The physician made the speaker realize that he alone had the ability to conquer his mental and physical dependency on the crutches. Without the help of the crutches, the speaker essentially cures himself through confidence and self-reliance. The speaker learns that he has the mental and physical capabilities to cure himself and no longer relies on his crutches to help him walk.