This quote explores the contrasting behaviors of friends and enemies. According to Thoreau, enemies are often more open and vocal about their intentions. They "publish" themselves, meaning they make their negative feelings or intentions known to others. They "declare war," which means they openly express their opposition or hostility. This is a metaphorical way of saying that enemies are not afraid to express their negative feelings and intentions.
On the other hand, friends "never declare their love." This suggests that friends often express their affection and support in more subtle, less overt ways. They may not make grand gestures or proclamations, but their love and support are nonetheless real and valuable. This can be seen as a commentary on the nature of true friendship, which is often characterized by quiet, steady support rather than grand gestures or declarations.
Applying this idea to today’s world or personal development, it could be said that individuals should be aware of the different ways in which people express their feelings and intentions. It’s important to recognize that not everyone who is vocal about their feelings or intentions is necessarily a friend, and not everyone who is quiet about their feelings or intentions is necessarily an enemy.
In the context of personal development, this quote could be interpreted as a reminder to appreciate the quiet, steady support of true friends. It could also be seen as a call to be more discerning in recognizing and responding to the intentions of others. Just as enemies "publish" themselves and "declare war," individuals should be prepared to recognize and respond to negative intentions or hostility. At the same time, they should also appreciate the subtle, less overt expressions of love and support from their friends.