Acosmism, held in contrast or equivalent to pantheism, denies the reality of the universe, seeing it as ultimately illusory (the prefix "ἀ-" in Greek meaning negation; like "un-" in English), and only the infinite unmanifest Absolute as real.
"[4] In the Vedanta school of Hinduism, the perceived world is Maya that hides the Absolute and Ultimate Reality (Brahman).
Vedanta holds that liberation is the unfettered realization and understanding of these invisible principles, primarily that the individual Self (Soul) is the same as the Self in others and the Self in everything (Brahman).
[8] Michael Comans says that the purpose of Advaita Vedanta as stated in the Māṇḍῡkya Upaniṣhad is to reveal that there is a single Absolute Reality which underlies the cosmos, yet is inherently acosmic, and which constitutes the essential “core”, or “self” of all beings.
[10] Both have elements of ontological acosmism, where the material aspect of cosmos is considered an "illusion, appearance, incomplete reality" compared to that "which is spiritual, eternal, unchanging".
[16] Acosmism has been seen in the work of a number of Western philosophers, including Parmenides, Plato, Spinoza, Kant, Hegel, Schopenhauer, and British and American idealists, such as F.H.
Stace sees all philosophical acosmism as rooted in the mystical experience[broken anchor], whether or not the authors are aware of this.
Stace points out that most Western philosophers tend to a form of qualified acosmism, where the world is less real rather than utterly illusory.