The Spanish philosopher and writer Miguel de Unamuno y Jugo (1864-1936) was the earliest 20th-century thinker to arrive at a perspective on man and the world that can be described as existentialist.

The total preoccupation of the philosophy of Miguel de Unamuno was "the man of flesh and bone"--the concrete individual with his passions, needs, hopes, and fears as the context within which human thinking and speaking occur. Unamuno was specifically concerned with the problem of faith in the modern world--"the agony of Christianity." He concluded that the split between faith and reason, heart and head, could not be healed by reason; that modern man must remain in a paradoxical and agonizing tension between faith and doubt, his religious beliefs only passionate hopes in the teeth of skepticism. Unamuno intensely lived out this modern predicament of faith in his own life, and he has been called...