We review Ferreirós and Lassalle Casanave's recently publishedbook "El árbol de los números". The book is a result of the Brazilian-Spanish conference "Sobre la elucidación del concepto de número: cognición, lógica y práctica matemática" hosted in Sevilla in 2013, and collects new papers on History and Philosophy of Mathematics as well as Mathematical Practice. These papers present results of investigations in Cognitive Sciences, Logic and Epistemology of mathematical certainty. In this review we present a general overview of the papers' contents, and advance a critical analysis of them.39197103