Emerson's essay was on self-reliance. He used the quote "Ne te quaesiveris extra" which means to look within yourself, rather than to look outside for answers. He wanted his audience to be true to his/herself.
His main idea was supported by diction because he used sophisticated words to help get his point across. He was being true to himself and used the vocabulary that please him.
When Emerson wrote this, his tone seemed a little frustrated. He didn't want people to be ignorant any longer. He believed people were highly intelligent. he wanted his audience to be on his/herself.
Emerson's main idea was supported by syntax. He worded every sentence a certain way, because he was setting an example to his reader. He wanted the reader to be true to their selves, so that's what he did as well. He phrased things in the best way he knew how.
Maybe Emerson's essay would be helpful if our society was different and humanity wasn't so harsh, but wee were trained as though we were robots and if it wasn't the way adults trained us, it was wrong. our ideas are belittled because they were different. Though I do believe people should be self-reliant, we can't, at least no in this society.