Schopenhauer here offers a wholly negative argument concerning human interaction:

As boredom seems to be an evil of this kind, people band together to offer it a common resistance. The love of life is at bottom only the fear of death; and, in the same way, the social impulse does not rest directly upon the love of society, but upon the fear of solitude; it is not alone the charm of being in others’ company that people seek, it is the dreary oppression of being alone–the monotony of their own consciousness–that they would avoid.

Here is the argument broken down:

Proposition one: Boredom is an evil.

Proposition two: Solitude leads to boredom.

Conclusion: One fears solitude, because solitude will lead to boredom.

Proof of the propositions:  Why is there boredom: (a) it is “dreary oppression;” and (b) one could become bored with one’s own thought, “the monotony of their consciousness”.

Proof of point: Therefore, we “band together” for the purpose of avoiding solitude (and thus, by extension, boredom).

Proof of point:  Analogy to life: One seeks life only due to the fear of death.

Corollary: The benefit of “society” is of margin value.

Having seen the argument in its parts, we can consider the elements severally.

Boredom: While it is unpleasant, it is not an unmitigated evil. For instance, boredom often provokes one to more useful endeavors.  This is related to the nature of solitude.

Solitude: He pick up on this point below in the form of an argument that for the “great”, solitude is not a burden but a benefit because I am alone with my own contemplation.

This leads to a subtle element of this argument: solitude leads to boredom for you lesser sorts; but for me!

Again, there is the irony of writing a book: the book is a social act. It is communication from the author to the reader. And so his solitude argument is not nearly as strong as it may seem.

But there is more. In solitary contemplation, one thinks about not merely raw nature without any social content. If one thinks in a language, that internal language is a matter of social content. No one looks upon the world as complete innocent. When Schopenhauer looked at the physical world without any human present, he still took to it the volume of human learning he had obtained from social content.

And so one person may be more or less solitary than others, but it is always relative.  A person who rejects all time alone or all time with others would limited in some ways.

But since it is Schopenhauer in the dock, let’s consider a truly solitary figure. Let us suppose this man thought the grandest and most valuable thoughts. What could would his contemplations be? What is the value of a human thought never communicated?