Philosopher, alchemist, and privateer, Kenelm Digby (1603-1665) cut a striking figure across Europe in the middle of the 17th century. Digby corresponded with Galileo, Descartes, Gassendi, Gilbert and Harvey, and was one of the founding members of the Royal Society. In 1644 he published his major philosophical work, Two Treatises: Of Bodies and of Man's Soul - the first comprehensive philosophical work in the English language. In the Two Treatises Digby discussed at length a vast array of philosophical ideas: elements, matter, mechanism, motion, force and causation, as well as sensation, perception, memory, imagination, intellect, reason, and immortality. MacDonald's edition is the first scholarly edition of this great work since it went out of print in 1669: it offers a normalized text, copious annotations, and a lengthy introduction which situates Digby's ideas in the currents of 17th century philosophical thought.