When the concept of sustainability was brought to the global stage in the 1987 UN Brundtland Report, it emphasized the necessity of balancing the needs of current and future generations, including non-human life and nature. Potentially, it was momentum for a philosophical turn from linear, consumption-driven modernism to embracing a symbiotic and inseparable relationship between humans and nature, which would have also embraced Qianji Ye’s (銭啓明) concept of ecological civilization. Instead of such holistic transformation, however, most of the issues discussed with the concept sustainability are specific phenomena, and the specialization of respective participants compartmentalizes the discursive spaces. In this chapter, the author untangles the nature of sustainability discourse by analyzing intertextual relationships and word usage in the documents posted on the web. Data are 1744 files published between 2015 and 2023 and downloaded with sustainability-related keywords. It identifies three main subspaces of discourse. One focuses on social issues at the micro-level, which also highlights the role of education in value formation. The second is driven by the perspectives from natural science about biodiversity and nature. The third is about practical interventions involving the private sector and civil society organizations. After discussing the general trends of the discourse, the chapter also investigates if ecological education and its pedagogies play any role in comparison to environmental education. The word environmental is sprinkled everywhere in analyzed documents, while the reference to ecology is limited. The author will consider such differential treatments of two words as a matter of divorce between ontology and epistemology of sustainability, referring to the philosophical map she set.