The three-pillar concept of sustainability, often visualized as three intersecting circles, has become a widely accepted framework in sustainability discourse. This paper traces the origins and theoretical foundations of this concept, revealing that it emerged from various critiques of economic development in the early academic literature and the UN's efforts to reconcile economic growth with social and ecological concerns. The three-pillar model, while popular, lacks a theoretically rigorous foundation, leading to ambiguity in its operationalization. The diagram of three intersecting circles, first presented by Barbier in 1987, has become a common representation, though its interpretation has evolved over time. The concept of three pillars predates this diagram, but no single source provides a clear theoretical framework. The three-pillar paradigm, though dominant in literature, is not universally accepted, with some works incorporating additional pillars such as institutional, cultural, or technical aspects. The UN's Brundtland Report (1987) and Agenda 21 (1992) played a significant role in institutionalizing the concept of sustainable development, emphasizing the integration of economic, social, and environmental dimensions. The 2002 World Summit on Sustainable Development further reinforced the three-pillar model, leading to the adoption of the Sustainable Development Goals (SDGs) in 2015. Despite its prevalence, the three-pillar model remains contested, with debates over its theoretical basis and practical application. The paper highlights the complexity of sustainability discourse, noting that while the three-pillar model is widely used, its conceptual origins are multifaceted and not clearly defined. The integration of economic, social, and environmental aspects remains a central theme in sustainability discussions, though the precise meaning and operationalization of these pillars continue to be debated.The three-pillar concept of sustainability, often visualized as three intersecting circles, has become a widely accepted framework in sustainability discourse. This paper traces the origins and theoretical foundations of this concept, revealing that it emerged from various critiques of economic development in the early academic literature and the UN's efforts to reconcile economic growth with social and ecological concerns. The three-pillar model, while popular, lacks a theoretically rigorous foundation, leading to ambiguity in its operationalization. The diagram of three intersecting circles, first presented by Barbier in 1987, has become a common representation, though its interpretation has evolved over time. The concept of three pillars predates this diagram, but no single source provides a clear theoretical framework. The three-pillar paradigm, though dominant in literature, is not universally accepted, with some works incorporating additional pillars such as institutional, cultural, or technical aspects. The UN's Brundtland Report (1987) and Agenda 21 (1992) played a significant role in institutionalizing the concept of sustainable development, emphasizing the integration of economic, social, and environmental dimensions. The 2002 World Summit on Sustainable Development further reinforced the three-pillar model, leading to the adoption of the Sustainable Development Goals (SDGs) in 2015. Despite its prevalence, the three-pillar model remains contested, with debates over its theoretical basis and practical application. The paper highlights the complexity of sustainability discourse, noting that while the three-pillar model is widely used, its conceptual origins are multifaceted and not clearly defined. The integration of economic, social, and environmental aspects remains a central theme in sustainability discussions, though the precise meaning and operationalization of these pillars continue to be debated.