"If you want to know your true opinion of someone, watch the effect produced in you by the first sight of a letter from him"

This quote by Arthur Schopenhauer suggests that our real opinion of somebody can be revealed by our preliminary reaction to a letter from them. It indicates that our first instinctive response to a letter from someone can be a reflection of our real opinion of them. This could be translated as an idea that our opinion of somebody is based upon our emotional response to them, rather than our mindful thoughts. It might also be seen as a tip to be mindful of our initial reactions to people, as they might expose more about our opinion of them than we understand. Ultimately, this quote encourages us to be knowledgeable about our true opinion of someone, and to be sincere with ourselves about how we actually feel about them.