Emerson's very influential version of transcendentalism was based on the idea that each individual was not only created in the image of God, but was created equally and in a unique way. Humans are the manifestations of God's will on Earth, and the best way to express this is to behave according to one's true individual will.
While there are certain norms that are so widely accepted as to be obvious, Emerson's famous saying "Trust thyself" is a better guide to human behavior than lawbooks, scriptural passages, or the judgement of others. Emerson's view of individuality is perhaps best expressed in his view of "genius," which he says ts to "believe your own thought, to believe that what is true for you in your private heart is true for all men." Emerson is specifically writing against a culture of conformity whose guiding principle was "sensibility." He claimed that rather than allowing society to govern one's behavior, the genius would dictate to the world through his own example what true morality and genius was.
Aside from liberating American writers and artists from the burden of copying European styles and forms, this line of thinking could also be applied to the moral issues of one's day, including the slavery question. For this reason, many transcendentalists, including Emerson himself, became abolitionists, some very active.