List of contributors; Foreword Norman I. Platnick; Introduction David Williams, Quentin Wheeler and Michael Schmitt; 1. Mission impossible: the childhood and youth of Willi Hennig Willi E. R. Xylander; 2. Willi Hennig: a shy man behind a scientific revolution Michael Schmitt; 3. Willi Hennig's legacy in the Nordic countries Ole Seberg, Torbjørn Ekrem, Jaakko Hyvönen and Per Sundberg; 4. Hennigian systematics in France, a historical approach with a glimpse of sociology Pascal Tassy; 5. Are we all cladists? Andrew V. Z. Brower; 6. How much of Hennig is in present-day cladistics? Michael Schmitt; 7. The evolution of Willi Hennig's phylogenetic considerations Rainer Willmann; 8. What we all learned from Hennig Gareth Nelson; 9. Semaphoronts: 'the elements of biological systematics' Leandro C. S. Assis; 10. Why should cladograms be dichotomous? René Zaragüeta Bagils and Sophie Pécaud; 11. Hennig's auxiliary principle and reciprocal illumination revisited Randall D. Mooi and Anthony C. Gill; 12. Dispersalism and neodispersalism Malte C. Ebach and David M. Williams; 13. Molecular data in systematics: a promise fulfilled, a future beckoning Ward C. Wheeler and Gonzalo Giribet; 14. Hennig, Løvtrup, evolution and biology Robin Bruce; 15. Willi Hennig as Philosopher Olivier Reippel; 16. Hennig and hierarchies Charissa S. Varma; 17. Chain, tree, and network: the development of phylogenetic systematics in the context of genealogical visualization and information graphics Nobuhiro Minaka; 18. The relational view of phylogenetic hypotheses and what it tells us on the phylogeny/classification relation problem Stéphane Prin; 19. This struggle for survival: systematic biology and institutional leadership Quentin Wheeler; Index.