Emptiness (suññatâ, suñña) in early Buddhism has not gotten a lot of attention, but it is there in the Pali Nikayas and the Chinese Agamas. It generally has to do with negation, for example, something that is merely the absence of something. It can be argued that emptiness in the Pali Nikayas and the Chinese Agamas has none of the significance and importance attributed to the emptiness (shunyata) found in Mahayana. I think it is safe to say that in early Buddhism, emptiness was no big deal—it had not yet become a spectacular philosophical term.
In the Pali Nikayas, ‘suñña’ means, desolate, vacant, lonely, absent, quiet, secluded, which has no special philosophical sense attached to it. A monk went into the forest and found an empty place and did meditation. As far as meditation is concerned, one can abide in the abode of emptiness (suññatâ-vihâra) which is empty of delusion, hatred, and craving (the three poisons). Also, the world is empty of the self. Finite things like the eye are also empty of the self. Material shape is empty of the self and so on. In one discourse in the Samyutta-Nikaya the Five Aggregates—never the good guys—are regarded as empty and not the self.
“Friend Kotthita, bhikkhu who is an arahant should carefully attend to these five aggregates subject to clinging as impermanent, as suffering, as a disease, as a tumor, as a dart, as misery, as an affliction, as alien, as disintegrating, as empty [suññato], as not the self [anattâ]” (S. iii. 168-169).
If we crave the Five Aggregates, being unable to distinguish (prajñâ) false reality (what is not the self) from true reality (the self), we come to suffer the same fate as the aggregates such as misery, affliction and being empty. Later on in Buddhism, the Five Aggregate formulation in which each aggregate is not the self will change.
"Born materiality is empty of sabhava (sabhavena suññam); disappeared materiality is both changed and empty. Born feeling is empty of sabhava; disappeared feeling is both changed and empty ... Born conceptualization ... Born volitions ... Born consciousness ... Born becoming is empty of sabhava; disappeared becoming is both changed and empty. This is ‘empty in terms of change’” (Patisambhidamagga ii.178 in the Treatise on Voidness).
Later, the above changes in the familiar first part of the Heart Sutra.
When Bodhisattva Avalokiteshvara was engaged in the practice of Prajñâ-pâramita, he beheld that the five aggregates are empty of own-being (svabhâva shûnyâm/sabhavena suññam).
Here, O Sariputra, materiality is emptiness and the very emptiness is materiality; emptiness does not differ from materiality, materiality does not differ from emptiness, whatever is emptiness, that is materiality, the same is true of feelings, conceptualization, volitions, and consciousness.
All this serves to obfuscate the original Pali that the Five Aggregates are empty of self, or the same, not the self which further means, we shouldn't identify our true self, or Buddha-nature, with the aggregates. Much later in Mahayana, the Buddha’s absolute body becomes the Svabhâva-kaya, the own-being body. Amazing!