From the pen of Spanish Nobel Laureate, Santiago Ram n y Cajal (1852-1934), the visionary of science nicknamed "Don Quixote of the Microscope," comes this essay, based on a 1905 lecture during the celebrations that marked the tricentennial of the "Ingenioso hidalgo de La Mancha." It is a mighty knock and a romantic fustigator against the awkward materialism that has been reigning in modern times. The text bespeaks the Cajalian spirit in the best possible manner, the deep love for science, and a unique vision of Spanish culture. Further, it offers a new outlook on Cervantes and his hero, highly praised later by educators. In Cajal's view, Don Quixote is not a madman, but a gentleman with solid ideas who consciously chose to be madly loyal to his convictions and duties; the hidalgo is an ideal of humanity, magnificence and justice; those values, instead of being signs of illness, must always be involved in any true science.