Question

How does an unsuccessful artist bring optimism in another person's life "The Last Leaf" ?

Answer 1

An unsuccessful artist drew the last leaf(his first and last masterpiece of his life since he was caught by pneumonia while he was painting that leaf on that stormy night). He made it and died giving a hope to the pneumonic patient who was comparing her life with the leaves of the oak tree in front of her window. that last leaf drawn by him gave her the will to live. 
Hope this will help u...

Answer 2

In the story last leaf we see that a girl named Johnsy has lost all her hopes in living. She says when the last leaf on the ivy vine falls, she too will fall (die) with it. Johnsy seems to be very pessimistic. On the other hand, her friend Sue wants her to be more optimistic.
When Sue narrates the story to Mr. Behrman, Mr. Behrman thinks that Johsny's thought is very silly. Mr. Behrman had always wanted to paint a masterpiece and as we see by the end of the story, he painted a leaf on the wall where the ivy vine grew just to bring positivity back in Johnny's life. It was because of him that Johnsy had a better outlook in life and believed she would live.
Mr. Behrman sacrificed his life for Johnsy.


Hope this helps!