天台所立之三諦三觀也。就所觀之理，謂為三諦，就能觀之智，謂為三觀。觀一念之心無相為空，觀此心具一切法為假，觀此二者不二為中。空以破一切法，假以立一切法，中以妙一切法。此三者為一法之異名，故謂為即空即假即中。祖庭事苑曰：「天台智者以龍樹偈云：因緣所生法，我說即是空，亦名為假名，亦名中道義。乃依一心三諦之理，示三止三觀。嘗云：破一切惑，莫盛乎空。建一切法，莫盛乎假。究竟一切性，莫大乎中。故一空一切空，無假無中無不空。一假一切假，無空無中無不假。一中一切中，無假無空無不中。」
Unreality, reality, and the middle or mean doctrine; noumenon, phenomenon, and the principle or absolute which unifies both. 空Unreality, that things do not exist in reality; 假 reality, that things exist though in "derived" or "borrowed" form, consisting of elements which are permanent; 中 the "middle" doctrine of the Madhyamaka School, which denies both positions in the interests of the transcendental, or absolute. 空以破一切法, 假以立一切法, 中以妙一切法 other 即空即假即中. śūnya(universality) annihilates all relativities, particularity establishes all relativities, the middle path transcends and unites all relativities. Tiantai asserts that there is no contradiction in them and calls them a unity, the one including the other 即空即假即中.
一空假中 法界之諸法，理體本來空寂，謂之空；森羅之諸法係由因緣而生，謂之假；非空非假，乃絕對之理，謂之中。空假中係天台宗所立之三諦三觀。就所觀不虛妄實相之理而言，空假中稱為三諦；就能觀此理之智而言，則稱為三觀。「空」以破一切法，「假」以立一切法，「中」以妙一切法。此三者為一法之異名，故謂即空即假即中。（參閱「三諦」910）p4386
空假中 天台智者以龍樹偈云“因緣所生法，我說即是空。亦名為假名，亦名中道義。”乃依一心三諦之理，示三止三觀。甞云“破一切惑，莫盛乎空；建一切法，莫盛乎假；究竟一切性，莫大乎中。故一空一切空，無假、無中、無不空；一假一切假，無空、無中、無不假；一中一切中，無假、無空、無不中。”如摩醯首羅天之三目，非縱橫，竝別故也。
見三諦或三觀條。