The Merchant Prince Reprint edition

Despite his lack of physical stature, the five-foot-tall John Dee was a towering figure in Renaissance Europe: to royalty, enemy to the vicious de Medici clan -- and confidant of Dyckson, a member of the alien race known as the Roc.
Ancient and wise, the Roc have come to Earth to observe the evolution of humanity, not to interfere. But during the course of his studies, Dyckson has come to call Dee friend. When the de Medicis arrest Dee in Venice, Dyckson chooses to save his friend from prison and leave him in suspended animation until the year 2099. The "philosopher of Albion" wakes in a confusing future where humanity is on the brink of developing the ultimate weapon -- a weapon that will mean the destruction of the human race!
The only thing that can prevent Armageddon is a genius from the past -- but can even the great John Dee save humanity from itself?