Heart Sutra is the dhamma, the teaching, the practice and the realization

Just as any other kind of Sutra, the Heart Sutra is the selfless impermanent name and form of the dhamma, the teaching, the practice, as well as the realization of Selflessness and Impermanence in all the names and forms, including the selfless limited physical body and the selfless perceptive cognitive assertive intellectual emotional thinking mind, transcending duality and separateness, void of suffering and the end of suffering.

The dhamma, the teaching, the practice, the realization, exists for the minds that perceive the suffering of restless selfless impermanent changes under the presence of the veil of ignorance.

The dhamma, the teaching, the practice, the realization, has no cause to be existing for the minds that are void of the veil of ignorance and suffering. The dhamma, the teaching, the practice, the realization, is non-existent to the selfless ignorance-free non-grasping mind, just as suffering doesn't exist upon the annihilation of the veil of ignorance, and there's no 'I' existing to be attaching and identifying towards selfless modification of the perceptive thinking mind perceiving all kinds of impermanent names and forms arising, changing and passing away, selflessly.

Shadow exists under the presence of light. Upon the absence of light, shadow doesn't exist.

'I' exists under the veil of ignorance. Upon the absence of the veil of ignorance, 'I' doesn't exist.

The idea of 'I' and the suffering that arise along with the idea of 'I', exist due to the presence of the veil of ignorance. And hence, there's the cause for the arising of the path towards the end of suffering, or the annihilation of the veil of ignorance.

The idea of 'I' and the suffering that arise along with the idea of 'I', don't exist upon the absence of the veil of ignorance. And hence, there's no cause for the existence of the path towards the end of suffering, or the annihilation of the veil of ignorance.

All is dhamma.

And yet,

Contradictory under the presence of the veil of ignorance, while non-contradictory under the absence of the veil of ignorance, not only that there's no 'I', there's no ignorance, no end of ignorance, no wisdom, no gain, no dhamma, no teaching, no practice, no realization, no eyes (sights), no ears (sounds), no nose (smells), no tongue (tastes), no body (senses, sense organs, sensations), no mind (thoughts, feelings, emotions), no consciousness, no suffering, no end of suffering, no increase, no decrease, no impurity, no purity. Merely selfless impermanent names and forms arising, changing and passing away under the nature's law of cause and effect.

Without direct realization towards the dhamma of selflessness and impermanence, without transcending selfless impermanent names and forms, duality and separateness, just by chanting the Heart Sutra or the mantra repeatedly for countless times, the mind is not free.

Inquire the truth of everything, including all the teachings of buddhism and/or yoga.