The Italian mathematician Mario Pieri (1860-1913) had a significant, yet somewhat underappreciated impact on several branches of mathematics, particularly on the development of algebraic geometry and the foundations of mathematics in the years around the turn of the 20th century. This book comprehensively examining Pieri's life, mathematical work and influence in such diverse fields as mathematical logic, algebraic geometry, number theory, inversive geometry, vector analysis, and differential geometry. This work is a combination of engaging exposition, little-known historical information, exhaustive references and an excellent index.