Paraphrase "Superfluous wealth can buy superfluities only. Money is not required to buy one necessary of the soul."

Superfluous
items are those that are unneeded, that are more than enough. Thoreau is saying in the first
sentence that unneeded wealth can only buy us unneeded things. These things distract us from the
essentials that are truly important in life.

We tend to view money as the
most important item to attain. Thoreau says in the second sentence that on the contrary, money
can't buy us the things the soul truly needs.

Thoreau makes these statements
in the context of arguing for the value of owning far fewer material goods. Having fewer goods
actually makes our lives better, not worse. As Thoreau puts it:

if you cannot buy books and newspapers, for instance, you are but confined to the most
significant and vital experiences ... It is life near the bone where it is sweetest.

Thoreau states a little further on that money matters far less than
truth. He recounts attending a party full of dishonesty and insincerity. Despite the fine wine
and food, Thoreau went away feeling hungry.

Throughout ,
Thoreau pounds away at his central point: the pursuit of ever more material goods hurts us more
than helps us. We can experience life more fully and truly when we live
simply.