In the digital age of advanced technology and abundant material wealth, humanity is trapped in a fog of value cognition: digital commodities can be infinitely replicated, artificial intelligence generates content independently, and data is hailed as the "oil of the new era". Claims such as "value creation without labor", "AI creating wealth independently", and "inherent value of data" are rampant, pushing a classic proposition to the forefront—Is living labor still the sole source of value? Who are the true creators of value in the digital age? Only One Source: On Living Labor and Value Creation (DOI:10.5281/zenodo.18832912) is a direct response to this core question of our times, and a significant academic work that challenges the myths of digital value and upholds and develops the Marxist labor theory of value. Rooted in the foundation of Marxist political economy, this book directly addresses the impacts and challenges posed by the digital economy to traditional value theories. Breaking free from inherent theoretical constraints, it pioneers a new definition of value: Value is the degree of human transformation of nature and human advancement of society. This definition grounds the abstract concept of value in perceptible and measurable realistic dimensions, bridging the interpretative gap between classic theories and contemporary economic phenomena, and providing a new anchor for understanding the value logic of the digital age. With this new definition as the fulcrum, the book deconstructs and refutes three core myths surrounding the source of value in the digital age layer by layer: it clarifies the essential difference between the production and replication of digital commodities, revealing that their value stems from the sustained living labor of users in the process of use; it delves into the underlying logic of artificial intelligence, proving that it has never been divorced from the support of human labor and is merely a tool rather than a subject of value creation; it redefines the two categories of data sources, pointing out that seemingly "naturally existing" data cannot be separated from the involvement of living labor in the entire chain from collection to value realization. Through incisive theoretical analysis and practical dissection, the book ultimately demonstrates its core conclusion: No matter how technology evolves or how capital packages itself, living labor—the human transformation of nature and human advancement of society—remains the sole source of value. Digital commodities, AI, and data that are touted as "creating value independently" are ultimately only tools and intermediaries for value creation. Behind all the myths of digital value lies capital's monopoly on digital means of production, as well as the expropriation and deliberate concealment of workers' living labor. This book is a core supporting academic achievement of The Contemporary Dimension Upgrade of Capital (DOI:10.5281/zenodo.18244088), and the two form a complete logical chain of "diagnosis and defense": the latter reveals the colonial logic of digital capital over the entire process of labor power production and reproduction, while the former returns to the origin of value and lays a solid theoretical foundation for the emancipatory program of the latter. As two sides of the same coin, they conduct an in-depth critique of the new forms of exploitation in digital capitalism and realize the contemporary development of the Marxist labor theory of value. They provide a unified political economic framework for understanding the economic essence of the digital age and recognizing the truth of capital exploitation, and further help us in the digital age to reaffirm the value of labor and clarify our subject status as creators of value.