Less technically, public domain properties are those which “The Man” cannot take away. You are free to keep pubic domain materials where you wish, access them when you wish, and use them how you wish. All without permission from anyone. Ever. After all, it is your property.
This elevates access to the public domain into rarified air. Right up there next to, “Life, Liberty and the pursuit of Happiness” as an unalienable right.
“That to secure these rights, Governments are instituted among Men.”
Thomas Jefferson
However, for property as with life and liberty—though it is crucial for the government to protect these for our benefit—it is undesirable for the government to possess these for our benefit.
The same holds true for The Public Domain.