Preface A remark on notation Acknowledgments Chapter 1 Expository articles 1.1 An explicitly solvable nonlinear wave equation 1.2 Infinite fields, finite fields, and the Ax-Grothendieck theorem 1.3 Sailing into the wind or faster than the wind 1.4 The completeness and compactness theorems of first-order logic 1.5 Talagrand's concentration inequality 1.6 The Szemeredi-Trotter theorem and the cell decomposition 1.7 Benford's law, Zipf's law, and the Pareto distribution 1.8 Selberg's limit theorem for the Riemann zeta function on the critical line 1.9 P = NP, relativisation, and multiple-choice exams 1.10 Moser's entropy compression argument 1.11 The AKS primality test 1.12 The prime number theorem in arithmetic progressions, and dueling conspiracies 1.13 Mazur's swindle 1.14 Grothendieck's definition of a group 1.15 The \