The concept is fundamental to Mahāyāna philosophy, implying the absolute, the ultimate source and character of all phenomena. In general Mahāyāna usage it indicates the absolute reality which transcends the multitude of forms in the phenomenal world. It is regarded as being identical with the Dharma-body 法身, being ineffable and inapprehensible by the unenlightened. It is regarded, on the one hand, as real existence 實有, and on the other hand, as emptiness 空. It is the underlying reality upon which all phenomenal existence depends.

In Yogâcāra, thusness is identified with the perfectly real nature 圓成實性, which is considered the underlying nature of all things, although not their producer (which is the ālayavijñāna 阿賴耶識). Thusness is perceived by the practitioner in varying degrees only in the ten grounds 十地.

In the Awakening of Faith, thusness is regarded as the mind of sentient beings, being distinguished into unchanging thusness 不變眞如 and conditioned thusness 隨緣眞如, the former being unchangeable and always pure, while the latter, subject to activation by nescience 無明 gives rise to the various phenomena of existence. The buddha-nature 佛性 is generally regarded as thusness inherent in unenlightened sentient beings. Cf. 如來藏.

The Sanskrit bhūtatathatā is transliterated as 部多多他多. It is also called 自性淸淨心 self-existent pure mind;實相 reality; Dharma-realm 法界; Dharma-nature; 法性; emptiness 空; non-emptiness 不空; formless 無相; uncreated 無生; without nature 無性 without nature.