Rūpaṃ śūnyatā śūnyataiva rūpaṃ; rūpām na pṛthak śūnyatā śunyatāyā na pṛthag rūpaṃ; yad rūpaṃ sā śūnyatā; yad śūnyatā tad rūpaṃ.
Form is emptiness, emptiness is form,
Emptiness is not differ from form, form is not differ from emptiness,
Whatever is form is emptiness, whatever is emptiness is form.
( Prajna Paramita Hrdaya Sutram )
Sabbe dhamma anatta
All of the dharmas ( both conditioned or unconditioned things ) are not self.
( Dhammapada )
The Heart Sutra speaks of the concept of ‘Emptiness’ while the Dhammapada speaks of the concept of ‘Non-Self’, but in my point of view, these two concepts seems to relate to one another. My opinion is that :
Emptiness means that all phenomenons and structures of the universe don’t have an ‘absolute and unchanging core’, so there is no ‘core’ at all, it’s totally ‘empty’.
While Non-Self means that all phenomenons including the structure of the universe don’t have a ‘core of self’ or ‘personality’, and even phenomenons referred to as ‘consciousness of beings’ are actually not a ‘core of self’ but more like an ‘illusory of self’.
If these two concepts are all linked to the concept of ‘Nibbana’, then it is fits, Nibbana is also empty of the ‘core of self’, even an absolute universal laws such as the laws of physics are also empty of ‘the core of self’, these laws are ‘Impersonal’, as Stephen Hawking said…