SIR KENELM DIGBY’S “Observations upon Religio Medici,” addressed to the Earl of Dorset and published in 1643, is perhaps the closest approximation made during the seventeenth century to the critical review of the nineteenth. Though not an original thinker, Digby has a clear and interesting style, and when he writes it is from the fullness of a highly diversified experience. Born in Buckinghamshire, England, in 1603, he had the disadvantage of the ill repute attaching to his father’s part in the Guy Fawkes plot, but he overcame it and was in high favor with the Stuarts. Banished as a royalist in 1643, he returned after the Restoration, as chancellor to Queen Henrietta Maria. He had traveled extensively in Europe, visiting celebrated philosophers, and he seems to have persuaded himself that he had occult powers such as were claimed by the Rosicrucians. Besides the “Observations upon Religio Medici,” he wrote “A Treatise of the Nature of Bodies,” “A Treatise Declaring the Operation of Man’s Soul,” and “A Discourse Concerning the Vegetation of Plants.”