This clear, direct, and accurate translation provides an excellent introduction to Cajal's work, making accessible for the first time the ideas that led Cajal to favor the neuron doctrine that revolutionized neuroscience and won for him the Nobel Prize in medicine in 1906. Santiago Ram n y Cajal (1852-1934) is widely thought of as the founder of modern neuroscience; and his work is more frequently cited than that of any other scientist in the field...