They do not believe in each other because they are forever changing. This is natural as nature itself, and this is what keeps our mental life moving on. This minor perceptual shift makes all the difference between freedom and bondage. For Emerson, living in the present and acknowledging it was of the highest importance. There was no need to jump on a soap box to teach these lessons as they are natural and only require a personal awareness and responsiability to learn them.
Silence can be as good as any argument because it stands in respect to nature.
Good and evil, true and false are all ideas created by man in order to make judgments. Nature does not make judgments but works in accord with its willingness to witness and be a testament to the present moment. Embracing our nature is what Emerson has eloquently asked us to do.