Book excerpt: The work of Jean Mawhin covers different aspects of the theory of differential equations and nonlinear analysis. On the occasion of his sixtieth birthday, a group of mathematicians gathered in Sevilla, Spain, in April 2003 to honor his mathematical achievements as well as his unique personality. This book provides an extraordinary view of a number of ground-breaking ideas and methods in nonlinear analysis and differential equations. List of Contributors: H Amann, M Delgado, J L Gimez, A M Krasnoselskij, E Liz, J Mawhin, P Quittner, B P Rynne, L Sanchez, K Schmitt, J R Ward, F Zanolin, and others. Contents: A Priori Bounds for the Positive Solutions of Super-Linear Indefinite Weighted Elliptic Problems (S Cano-Casanova); Parametric Excitation in a Predator-Prey Model (A C Casal & A S Somolinos); Reasons for a Homage (M Delgado); Bifurcation through Higher Order Terms for Problems at Resonance (M Garc a-Huidobro et al.); Malthus, Verhulst, and the Metasolutions (J Lpez-Gmez); Axiomatizing the Algebraic Multiplicity (C Mora-Corral); Instability of Periodic Solutions Obtained by Minimization (R Ortega); Periodic Solutions of Second Order Equations OCo A Variational Approach (K Schmitt); Some Indefinite Nonlinear Eigenvalue Problems (A Suirez); and other papers. Readership: Researchers in the fields of ordinary differential equations, partial differential equations and nonlinear analysis."