I don't believe I have ever before read a microscopy textbook from cover to cover — but this one, reader, I did. Its two editors, Taekjip Ha and Paul Selvin, have set out to assemble a manual for cell biologists who want to extend their technical repertoires to include single-molecule techniques. They have succeeded admirably, and as a bonus the book provides a fascinating insight into where the technical limits lie, of how we stand — as the authors suggest in their introduction — at the beginning of a new era of single-molecule-based cell biology. If molecular cell biology had an agenda, then near the top of the list would be the need to understand how the biology of cells arises out of the properties and behaviours of individual molecules. Single molecules still hold considerable mystery. For the most part, the world of our everyday experience comprises multimolecule phenomena, and the familiar language of cell biology is adapted to describe these phenomena. As we zoom in to the single-molecule level, unfamiliar things start to happen. Events become stochastic. Structures become probabilistic distributions of different structures. Everything jiggles about, so that even the idea of a given object being in a particular fixed position needs careful consideration and qualification.