Lionel's text, to this point, brings us to 2008. Some further comments are therefore useful, both to round out Lionel's thoughts, and to relate his ideas more fully to current research in the field, now a rapidly expanding one. Lionel's unique voice is apparent throughout the book. It is not intended as a guide book to quantitative work in development – Biological Physics of the Developing Embryo by Forgacs and Newman (2005) is a good example of this. Nor is it a broad survey of pattern-formation processes and how they apply in biology – Philip Ball's Nature's Patterns (2009) is exemplary in that regard. Rather, the focus is on how one goes about exploring and testing the potential of a particular theory, developed in this case first by Turing and extended since by others; it is as much a commentary on how to construct a quantitative biology as it is an examination of particular dynamic issues in development. Lionel began his work in biology in the early 1970s, and was part of the blossoming of ideas in self-organization and how they might apply in biology. As chronicled here, these ideas gained a degree of acceptance by a segment of the developmental community, despite the division of cultures Lionel has described. The 1990s, though, heralded increasingly powerful techniques for manipulating gene regulation, with an increasingly detailed mapping of the components of developmental pathways, and little emphasis on overall dynamic constraints for patterning.