This book deals with the economic sense of property rights, in other words, "who owns what?". Property rights are not defined uniformly across cultures since societies have discretion as to how to define those rights. In fact, they are very often not perfectly delineated. People can delineate those rights under the shadow of the law or ask a court to settle their case. The common view that commodities are homogenous entities with only one attribute gives rise to the conclusion that the right is either owned by someone or not owned. In real life, assets incorporate several attributes, whose ownership is not always perfectly delineated. Under certain circumstances it is too costly to measure and protect all assets' attributes. When circumstances change, conflicts can arise. Neoclassical literature instead assumes simplistically that transaction costs are zero and that all property rights are perfectly well delineated. Once you can take into consideration intermediate cases (common and private goods, environment, contractual rights etc) as Barzel does in this book, you can have a more complete model to price goods, which come logically from well-defined first principles. A must read for public economists and (why not?) lawyers.