The use of geometry to learn and study concepts and theories is common in many fields of study, including mathematics, physics, economics, and finance. Yet it is hardly the case in accounting. The book shows that the use of geometry is possible in accounting in order to present (record) accounting transactions (events) according to the double entry principle and explore the features and principles of double entry accounting. In doing so, the book uses geometric concepts and theories and various types of transaction examples. The geometric settings used to do so are two- and three-dimensional Cartesian spaces. The point, line, and space representing individual accounting events are referred to as the double entry (DE) point, DE line, DE square (or cube), and DE circle (or DE sphere) respectively of accounting events. For a given accounting event, these alternative geometric presentations are equivalent in that they all represent the same accounting event and reflect the same duality and balance features of the event or, more generally, the features and principles of double entry accounting.