I've learned a new word today: "mortmain". It refers specifically to the continued ownership of land by the church (therefore never reverting back to the crown and incurring no inheritance tax) and in general of the way the past can dictate the present in an oppressive way. The word literally means "dead hand", like a deceased owner still gripping a contract.
It struck me that such a concept applies very well to current copyright. After the term of copyright is over, artists are assumed to have been adequately compensated for their efforts in contributing to our culture, or it is similarly assumed that they will never quite make their money back. The work then reverts into the public domain. Currently, we have corporations owning perpetual copyrights (because they never die) and continuous pushes for extending copyright terms. This is all keeping works from going into public domain even long after the original creator is dead and long since compensated for his or her contribution to society through the arts. Mortmain. The dead hand of artists still grips their works from beyond the grave.
Mokalus of Borg
PS - If copyright were intended to be perpetual, that's how it would have been formulated in the beginning.
PPS - The optimal copyright term has been calculated at 14 years.