This book, and the other two volumes to follow soon after, offer the scientific community the works and thoughts of Santiago Ramon y Cajal by the faithful rendition of the original Spanish version of the "Texture of the Nervous System of Man and the Vertebrates" (1899-1904), with additional facts contained in the French translation (1909-1911). These non-English versions are being quoted an average of 200 times yearly in the scientific literature. Unique features of the present work include: only authorized English translation of the original Spanish text, adhering as much as possible to the letter, with correction of the obvious errors already predicted by Cajal in his preface; added facts appearing in the French version, with correction of old as well as new errors, the latter probably due to inaccuracies in translating into French some nuances of the Spanish language; and, uniform of nomenclature according to contemporary scientific English. The features also include: annotations on Cajal's changing concepts over time, the elucidation of certain structures that do not have present day equivalents, and explanations of the many symbols appearing in illustrations but not mentioned in the corresponding original legends; most illustrations are reproductions of Cajal's original art work, still extant at the Cajal Museum in Madrid, with cross references to figure numbers of the Spanish and French versions; citations are given by author and year in the text, with an alphabetical list at the end of the volume, completed and corrected for accuracy against original publications; and, taxonomy glossary of species appearing in the text, with present scientific names, and their colloquial English counterparts. In sum, the collection represents the 'definitive Cajal' to be used by scientists and scholars interested in the original writings of probably the most prominent neuroscientist of all times.