Examine The Battle of Books as an allegory.

In literary terms, an allegory can be described as a poem or story with a hidden meaning. In Swift's satirical work The Battle of the Books, the underlying meaning isn't especially well-hidden. Behind the literal battle of the books (fought out in the confines of a gentleman's library) lies the then-current argument about which epoch's literature was superior—ancient or modern. Swift comes down firmly on the side of the ancients. This was, after all, the position of his noble patron, Sir William Temple, and as Sir William's humble servant, Swift valiantly goes into bat for him.
Within the overall allegory there's a brief digression that is itself an allegory—an allegory within an allegory, if you will. This is the tale of the spider and the bee. The spider, who lives in the corner of one of the library's upper windows, curses a bee for carelessly destroying his intricately spun web. The bee responds by saying that he's doing nature's bidding by buzzing about from place to place, whereas the spider does nothing but sit around all day, spinning vast webs out of himself and his plentiful supply of "Dirt and Poison."
The point that Swift is making here is that the ancient authors, like the bee, gather their materials from nature, specifically human nature, in writing their enduring works of literature. Whereas modern authors, like the spider, draw upon themselves and their own narrow subjective experience of the world.
By drawing upon nature, the ancients were able to produce timeless works whose continuing relevance transcends the specific historical epochs in which they were written. As human nature is universal, Swift would argue, works of art grounded in a thoroughgoing fidelity to nature evince the same quality, allowing them to speak with authority to successive generations of men in different times and places.
However, the moderns cannot hope to aspire to such a happy condition. As their work is largely of a subjective, individual quality, it is destined not to endure beyond the period in which it is written. Hence the superiority of the ancients over the moderns in this epic battle of the books.