 As  Section 1.5  will detail, some models of what is ultimate nest, e.g., Shankara’s idea of Brahman is a species of Vedantic ideas of Brahman which in turn are species of Hindu ideas of Brahman. To simplify, this entry will use the term “model” for ideas of what is ultimate at all levels, and take a model’s target to be “the ultimate” if the modeler thinks what is ultimate is single or uncountable (as in models of e.g., Brahman, God and the Dao) or “ultimates” if multiple (as in polytheistic or perhaps communotheistic models).