Stamos' study deserves high praise. It is the most comprehensive survey of the literature on the question of "species" - how to define the term, how to classify it among other biological terms, how it was historically used and misused, how it relates to other questions of ontology (what there is) and epistemology (what do we know and how we get to know it), and how it is bound with serious philosophical questions about Universals (do they exist?, are they nothing but a collection of Individuals?) and Essentialism (does something have certain characteristics that are essential or secondary to its very nature and existence?), to name just two categories. The book is well organized, clearly written, broadly researched, and meticulously referenced…as such, this book should become a standard reference to anyone interested in biology form theoretical and practical perspectives alike.