A more subtle account of the experience of emptiness is to suggest that while an
ordinary being sees either conventional truth or else something like ultimate truth,((This is 'something like ultimate truth‘ or emptiness, because its own emptiness is not perceived. That is,it is conceived to be independent from the conventional, and one does not realize that it is the conventionalnature of conventional truth.))) the
Buddha sees both contemporaneously.
This would appear to be the idea behind Chi-Tsang‘s notion of concurrent insight, (cf. Koseki 1981) and it also seems to be Garfield‘s final view, where he claims, "nirvāṇa is only saṃsāra experienced as the Buddha experiences it" (1995, 333). The suggestion, then, is that the Buddha experiences both nirvana and saṃsāra at the same time, that is, by experiencing the conventional as conventional, he experiences the ultimate. Care is required, however, not to construe this dualistically, that is, the claim that the Buddha sees 'both‘ truths, does not imply that there are two things put together, an ultimate reality added to a conventional one.
This account still does not do justice to Mahāyāna nonduality. According to Aaron Koseki
"concurrent insight is not a theory of combination or union, but the perception of identity and interdependency" (Koseki 1981, 460), that is, the Buddha experiences only one thing,the relation between conventional and ultimate truth. This is what Nāgārjuna means,perhaps, by stating that emptiness is in fact dependent co-origination.
To sum up, if conventional things, such as trees and selves, are perceived as conventional, as arising and perishing in dependence upon each other, this amounts to
perceiving their emptiness.
It is only when we fail to see conventional things for what they are, and we assume they exist with svabhāva, that opposition between the two truths arises, and either one escapes us. Thus, ordinary beings sometimes see conventional truths and take them for ultimate truths, assuming that the things they perceive exist inherently, and they find themselves in saṃsāra. Otherwise, they sometimes glimpse something like emptiness, which they take to be a separate realm, perspective, or else, a reality that underlies ordinary experience, and which also exists with svabhāva.
The Buddha, on the other hand, in perceiving emptiness, sees conventional things in their ultimate nature, that is, he sees them as conventional and empty. He does not perceive anything different from conventional truth, nor does he perceive two things at the same time. Yet, I do not want to assert anything more about what the Buddha perceives as ultimate truth, for reasons that will become apparent.