Yogācāra works often define three basic modes or "natures" ("svabhāva") of experience. Jonathan Gold explains that "the three natures are all one reality viewed from three distinct angles. They are the appearance, the process, and the emptiness of that same apparent entity." According to Paul Williams, "all things which can be known can be subsumed under these Three Natures." Since this schema is Yogācāra's systematic explanation of the Buddhist doctrine of emptiness ("śūnyatā"), each of the three natures are also explained as having a lack of own-nature ("niḥsvabhāvatā")." Vasubandhu's "Trisvabhāva-nirdeśa" gives a brief definition of these three natures: "What appears is the dependent. How it appears is the fabricated. Because of being dependent on conditions. Because of being only fabrication. The eternal non-existence of the appearance as it is appears: That is known to be the perfected nature, because of being always the same. What appears there? The unreal fabrication. How does it appear? As a dual self. What is its nonexistence? That by which the nondual reality is there." In detail, three natures ("trisvabhāva") are: