The ancestors represent the traditional Jewish values that Tevye has been raised with. They tell him that he must uphold these values, even in the face of adversity. They also tell him that he must forgive Chava and accept her for who she is.
Tevye's dream is a way for him to work through his grief and come to terms with the changes that are happening in his life. By the end of the dream, he is able to accept Chava's decision and move on with his life.
Here are some of the key themes that are explored in the dream sequence:
Tradition vs. modernity: Tevye's dream pits the traditional Jewish values that he has been raised with against the modern, secular values that are becoming increasingly prevalent in Russian society. Tevye struggles to reconcile these two sets of values, and he ultimately comes to the realization that he must find a way to balance them in his own life.
Forgiveness: Tevye is initially unable to forgive Chava for eloping with a Russian peasant. He believes that she has disgraced the family, and he is ashamed of her. However, through the course of the dream, he comes to realize that he must forgive her. He understands that she is still his daughter, and that he loves her regardless of her choices.
Acceptance: Tevye's dream helps him to accept the fact that his life will never be the same again. He has lost his daughter, and his family has been torn apart. However, he also comes to realize that he must accept these changes and move on with his life. He finds strength and hope in the knowledge that he is still loved by his family and his community.
The dream sequence in Fiddler on the Roof is a powerful and moving meditation on the themes of tradition, forgiveness, and acceptance. It is a key moment in the play, and it helps to bring Tevye's story to a satisfying and poignant conclusion.