Emerson clearly attaches a great deal of importance to friendship, as one can see from his essay of the same name. He sees it in cosmic (rather than merely human) terms, as something that enables us to transcend our limited selves and partake of the eternal.
Not only does friendship transform the soul but it also transforms the earth itself. When one becomes attached to someone else, when one enters into friendship with another soul, the earth begins at once to look like a completely different place from what it once was. It makes “a young world” again, indicating perhaps that friendship recreates one's childhood years, a time of freedom and innocence.
In a particularly rhapsodic passage, Emerson claims that “the moment we indulge our affections,” the earth is “metamorphosed,” that is to say, transformed, to the extent that all everything bad—winter, night, boredom, tragedy—suddenly vanishes. As indeed do all duties.
Of course, Emerson is speaking metaphorically here. He doesn't literally mean that friendship can really make all the bad things go away. What he does mean, however, is that it can make us see the world in a much more positive light. The earth appears so much better thanks to the transformative powers of friendship.