Merlin, Gandalf, Voldemort--these well-known sorcerers from popular culture are famed for their amazing spells and spectacular magical powers. In ancient times, however, a wizard was actually a freelance intellectual whose main stock in trade was good advice, supported by a thorough education in agriculture, navigation, political and military science, languages, commerce, mathematics, medicine, and the natural sciences--in essence, the true Renaissance man.

John Michael Greer proposes a modern mage for uncertain times; one who possesses a startling array of practical skills gleaned...