A &quot;real-world&quot; library&#x27;s goal of knowledge-sharing is balanced with the need of the content-provider to make some money to support distribution and authoring of books.  The public pays taxes to fund libraries so that people who can&#x27;t afford to buy (or choose to not buy) particular books can still access them.  There&#x27;s a natural brake on distribution in that each copy can be checked out to at most one library patron at a time.<p>The most direct analogy carried over to the electronic space is e-book lending systems with built-in DRM.  These systems usually keep the N-number-of-copies-available-for-loan restriction in place.  Unlimited file-sharing does not at all resemble the balance between the-good-of-public-knowledge vs the-right-and-need-for-publishers-and-authors-to-make-money that a physical library model provides.