The Heart Sutra is said to be the most well-known and popular of Buddhist scriptures that have managed to come down to us, much like the 23rd Psalm is for Christians. Contained in it is the seemingly confounding but beautiful teaching of nothingness or emptiness. It is one of those things that are best understood or arrived at not with the brain trying to decipher its meaning. When you've achieved stillness and become more calm from absorbing it, then it gets better to understand. . . even if you still really don't!
As with many ancient writings, there have been many translations. I like the simple one below taken from this link -
Avalokiteshvara, the Bodhisattva of Compassion, meditating deeply on Perfection of Wisdom, saw clearly that the five aspects of human existence are empty, and so released himself from suffering. Answering the monk Sariputra, he said this:
Body is nothing more than emptiness,Which means...
emptiness is nothing more than body.
The body is exactly empty,
and emptiness is exactly body.
The other four aspects of human existence --
feeling, thought, will, and consciousness --
are likewise nothing more than emptiness,
and emptiness nothing more than they.
All things are empty:
Nothing is born, nothing dies,
nothing is pure, nothing is stained,
nothing increases and nothing decreases.
So, in emptiness, there is no body,
no feeling, no thought,
no will, no consciousness.
There are no eyes, no ears,
no nose, no tongue,
no body, no mind.
There is no seeing, no hearing,
no smelling, no tasting,
no touching, no imagining.
There is nothing seen, nor heard,
nor smelled, nor tasted,
nor touched, nor imagined.
There is no ignorance,
and no end to ignorance.
There is no old age and death,
and no end to old age and death.
There is no suffering, no cause of suffering,
no end to suffering, no path to follow.
There is no attainment of wisdom,
and no wisdom to attain.
The Bodhisattvas rely on the Perfection of Wisdom,
and so with no delusions,
they feel no fear,
and have Nirvana here and now.
All the Buddhas,
past, present, and future,
rely on the Perfection of Wisdom,
and live in full enlightenment.
The Perfection of Wisdom is the greatest mantra.
It is the clearest mantra,
the highest mantra,
the mantra that removes all suffering.
This is truth that cannot be doubted.
Say it so:Gaté,
gone fully over.
So be it!