Ever since Niels Jerne introduced the Darwinian principles of ‘variation and selection’ into immunology in 1955, the field has truly flourished. Immunologists can now claim an impressive record; during the past 40 years, they have deciphered a significant number of intricate molecular and cellular mechanisms. Indeed, the names of many immunologists enrich the list of Nobel Prize winners, confirming that this field has been at the forefront of biological research for many decades. Nearly 30 years ago, in a lecture at the Institut Pasteur in Paris, France, Jerne estimated that the number of immunologists in the world had tripled every 20 years from the late 19th century, to reach about 10 000 in 1970 (Jerne, 1974). This number is now likely to be above 40 000, and a paper in immunology is published, on average, every 15 minutes. Today, not only do we know many of the cell types, molecules and genes that protect us from disease‐causing agents, but immunology has also made a remarkable contribution to general biology. Jerne used to say that lymphocytes are the Escherichia coli of eukaryotes, and many advances in cell differentiation, the cell cycle, signalling, intracellular protein trafficking, DNA recombination and repair, and the regulation of gene expression owe their discovery to this extraordinary cell type. The study of the immune system has also contributed to an understanding of phenomena such as the evolution of gene complexes, the principles of cell migration and homing, homeostasis and cell turnover. And even although other biologists are often dismayed by the jargon and acronyms used by immunologists, ‘the antibody problem’ nevertheless fascinated the founding fathers of molecular biology, and this widespread interest in the essential problems of immunology continues to this day. > The paradox of today's immunology is that tremendous progress in basic science has been matched …