The phrase that correctly summarizes the main point of this text from the excerpt is "we are not always sure that those who advocate the truth are influenced by purer principles than their antagonists." From the phrase itself, you can see a clear picture of the main idea of what the story is about. About the principles of brought by humans and how are they able to follow this or not. Also, it is interjected that it may be a war of principles between the good and the bad one. How often the good one remain good by upholding his or her principles without leaning to the bad side.
