"I did not know then that pride was a wonderful thing, terrible thing, a seed that bears two vines, life and death." What does this quote mean?

In the story, Brother had forced Doodle to learn many things that no one thought he could do. However, Brother's motivation for helping Doodle was pride, because he did not want anyone to think of him as a person with a handicapped brother. At first, everyone is amazed at the things that Doodle can do. These extraordinary feats are metaphorically the first vine pride can bring. However, once Doodle became old enough to go to school, Brother forced him to learn how to run because Brother didn't want to be embarrassed at school by Doodle's weaknesses. However, in pushing Doodle to run, Brother pushes too hard and Doodle dies. This is the second vine that pride can bring, death. Doodle gains more of life because of Brother's pride but in the end Brother's pride destroys Doodle because he is forced to do something he simply cannot physically accomplish.