David Phillips was an outstanding scientist, one of the founding fathers of structural biology and a wise and influential figure in science and government. He started his research career with work on X-ray intensity statistics, then moved to small molecule crystallography, followed by protein crystallography and instrument design. Protein crystallography led to proposals for structure/function relationships, homology modeling, fundamental understanding of thermal motion, and several new protein structures of pharmaceutical interest. However, it is for his work with lysozyme that he will be most widely remembered. In 1966, he and the team, working at the Royal Institution in London, solved the first structure of an enzyme, lysozyme: from the structure it was immediately possible to put forward proposals for catalytic activity. The work first showed the power of protein crystallography to explain biological function in terms of physics and chemistry. It opened the way to the explosion in the number of protein structures that are now being determined with modern technology, and for the insights that these structures provide for the benefit of fundamental research, medicine, and agriculture.