This book aims at introducing the reader possessing some high school mathematics, to both the higher and the more fundamental developments of the basic themes of elementary mathematics. To this end most chapters begin with a series of elementary problems, behind whose diverting formulation more advanced mathematical ideas lie hidden. These are then made explicit and further developments explored, thereby deepening and broadening the reader's understanding of mathematics -- enabling him or her to see mathematics as a hologram. The book arose from a course for potential high school teachers of mathematics taught for several years at St. Petersburg University, and nearly every chapter ends with an interesting commentary on the relevance of its subject matter to the actual classroom setting. However it can be recommended to a much wider readership, including university--level mathematics majors; even the professional mathematician will derive much pleasurable instruction from reading it.