Looking at postmortem Buddhism it appears to me that emptiness (śūnyatā) has come to represent both the older conditionality (saṃskṛta) and unconditionality (asaṃskṛta).
From the point of view of phenomena or empirical reality (dharmas) emptiness means devoid of self-nature or svabhāva. In other words, there is nothing really real which exists in its own right. Nothing is independent or the same, self-dependent. The world we live in is unreal. It is the world of relativity.
From the point of view of the absolute or true reality, emptiness means that there is no manifoldness or diversity. It means also devoid of thought constructs. There is no plurality—only thatness (tathatā). This emptiness is also inexpressible by language and unthinkable.
It seems to me that we can apply the older forms ‘conditionality’ and ‘unconditionality’ with equal or better precision which does not fog over emptiness. Why, for example, does the Heart Sutra have to say that the five skandha or aggregates are ‘empty of svabhāva’? Just say, instead, that skandha are ‘empty of unconditionality’ (asaṃskṛta). This would work, given that nirvana is unconditioned. Then nobody in their right mind would look for the unconditioned (i.e., nirvana) in the conditioned. It ain’t there!
That all things are empty would mean, all things are empty of the unconditioned since ‘all things’ refers only to the conditioned. Turning to the Lankavatara Sutra:
That all things are devoid of self-nature means that there is a constant and uninterrupted becoming, a momentary change from one state of existence to another; seeing this, Mahāmati, all things are destitute of self-nature. So one speaks of all things having no self-nature.
What is really being said is that all things (conditionality) are empty of the unconditioned. Because of this lack of the unconditioned there is becoming, that is, constant change from one state to another which is the mark of the conditioned. So why look for the unconditioned (nirvana) in the conditioned?
Siddhartha's journey was to awaken to the unconditioned seeing, as a result, that the conditioned world was a phenomenalization of the unconditioned.