The Ecstasy of Influence

In Jonathan Lethem's "The Ecstasy of Influence" Lethem talks a lot about authors using other authors work. Some people may say that he is saying that plagiarism is okay. But in my opinion i think that he is just saying that most good ideas are built of other good ideas. He thinks that these others works can be used to build off of to make a good story. I think that building off other authors idea shouldn't be seen as shameful. I think so because if people didn't use others work to inspire work, people wouldn't be able to write these good works because they wouldn't have anything to inspire them.