The Heart Sutra is one of the most well-known Buddhist scriptures. It is part of the Mahayana Buddhist tradition, which includes both Zen and Tibetan Buddhism. It is part of a grouping of sutras commonly called the 'Perfection of Wisdom' (prajna-paramita) sutras, but is the shortest amongst them, normally spanning only a page or two depending on the translation (as opposed to the Large Sutra on Perfect Wisdom, which typically spans many hundreds of pages in translation.) Another unique feature of the Heart Sutra is that it ends with a mantra, or chant, that is said to directly represent and awaken the wisdom implicit in the sutra itself.

At the start of the sutra Avalokiteshvara, the Bodhisattva of Compassion, is asked by the monk Sariputra how one may study the prajna-paramita, or perfect wisdom. Avalokiteshvara begins his answer with:

"If a son or daughter wishes to study the profound Prajna-paramita, he must first get rid of all ideas of ego-selfness. Let him think thus: Personality? What is personality? Is it an enduring entity? Or is it made up of elements that pass away? Personality is made up of the five grasping aggregates: form, sensation, perception, discrimination, consciousness, all of which are empty of any self-substance. Form is emptiness, emptiness is not different from form, neither is form different from emptiness, indeed, emptiness is form." (all Heart Sutra quotes are from Dwight Goddard’s translation in A Buddhist Bible.)

Far from simple philosophy, this passage provides a framework for meditation. It is not meant to be understood intellectually, but to help a practitioner inquire into the nature of his own mind, perceptions, and sense of selfness. By looking first at our personality, the most external form of selfness for most of us, we can begin to see it as made up of the five aggregates of energy, and see that it is empty of inherent, eternal identity.

From here, Avalokiteshvara describes the emptiness of each of the five aggregates – form, sensation, perception, discrimination and consciousness. In modern terms, each might be understood as an aspect of mind, a filter through which we perceive the world. By deconstructing the workings of each one through inquiry meditation, we can uncover pure awareness itself, and from this awaken to Prajna-paramita.

When first coming upon the Heart Sutra, many people are surprised that it is not a meditation on compassion, or metta (lovingkindness), as this is what they associate 'Heart' with. But in most Asian languages, Tibetan included, the word for 'heart' and 'mind' are the same. 'Mindfulness' practice is 'heartfulness' practice. Inquiry into the true nature of all phenomena brings us to the heart of our own being, of all beings - the connection from which compassion springs.

This is a lifelong, or even multi-life long, practice for most seekers, with many potential misunderstandings along the way. The most prevalent is the tendency of our mind to make Buddhist teachings, and Prajna-paramita, themselves into concepts within our own mind. Once we have made them into mental concepts, we relate to them as 'things', as objects within the mind, that have form - not empty. Avalokiteshvara attempts to help cut through this delusion towards the end of the sutra:

"There is no knowledge of Nirvana, there is no obtaining of Nirvana, there is no not obtaining of Nirvana....Why is there no obtaining of Nirvana? Because Nirvana is the realm of no 'thingness.' If the ego-soul of personality was an enduring entity it could not obtain Nirvana....So long as a man is seeking highest perfect wisdom, he is still abiding in the realm of consciousness. If he is to realize Nirvana, he must pass beyond consciousness."

The Heart Sutra ends with a mantra, which when transliterated from Sanskrit is usually rendered as:

Gaté,
gaté,
paragaté,
parasamgaté.
Bodhi!
Svaha!

Which translates approximately as:

Gone,
gone,
gone over,
gone fully over.
Awakened!
So be it!

The mantra itself is a tool for realizing prajna-paramita, as well as a representation of it in sound.