Early books included "The Philosophy of Justice Between God and Man" (1851) and "Optimism: The Lesson of Ages" (1860), a Christian mystical vision of the pursuit of happiness from Blood's distinctly American perspective; on the title page of the book, Blood described it as "A compendium of democratic theology, designed to illustrate necessities whereby all things are as they are, and to reconcile the discontents of men with the perfect love and power of ever-present God."