We need a story or the rest of the information to figure out the answer
It is both since it can be like surrounding and availability or approximately. Depends on the sentence, though.
Answer:
When Thoreau says <em>superfluous wealth</em> he refers to money that is not needed or there is more of it than enough and that with all that money can be bought just things that we do not need. Those things make us blind for what should be really important in life. As he goes on in the second sentence - we can have money, but we can not buy what our soul needs. Life can be experienced far more fully when living simply.
