Most of the important astronomers and natural philosophers (as well as artists) in the 16th and 17th centuries depended on the patronage of powerful religious or political figures to fund their work. Patronage networks extended all the way from Emperors and Popes to regional nobles to artisans to peasants; even university positions were based to some extent on patronage. Scholarly careers in this period were driven by patronage, often starting in undistinguished universities or local schools or courts, and traveling closer or farther from centers of power as their fortunes rose and fell.