The drastrdrsyayoh samyogah heyahetuh sutra states about the root cause of pain that rises up when the seer and the seen amalgamates. Pain never ceases, until these two are disunited. One must be wise enough to distinguish intelligence from the temptations of materialistic wonders. Otherwise, one is enmeshed within the dangerous arena of external objects. Once the intelligence stops oscillating between the brain and the heart, one is sure to achieve true meditation.

drastra seer, self, purusa
drsyayoh the seen, the known, nature
samyogah union, association, conjunction, connection, junction, mingling
heyah to be relinquished, to be avoided
hetuh cause, ground, reason, purpose

The cause of pain is the association or identification of the seer (atmi) with the seen (prakrti) and the remedy lies in their dissociation.

A prudent person notices that inner harmony is interrupted when the mind lets itself be lured into indiscriminately sampling the world of phenomena. He tries to remain free by avoiding material attachment, in which objects attract the intelligence like a magnet and the self is tempted into an illusory relationship with the external, seen world, provoking pleasures and pains. The intelligence is the vehicle closest to the soul, which must be cautious of its influence if the seer is to stay free. Or else, intelligence entangles the seer into a painful relationship with external objects. As long as intelligence is indiscriminating, there is suffering. The moment it develops discriminative power, it realises its source, and unites with the seer. Then there is transparency between the seer and seen, allowing free, uncontaminated passage between them.

The seat of the ego or small self is the seat of the brain, and the seat of the great Self is within the spiritual heart. Though intelligence links the head and the heart, it vacillates between the two. This vacillation stops through right knowledge and understanding. Intelligence is then transformed - free from polarity, pure and unbiased. This is true meditation, in which ego dissolves, allowing the great Self (purusa) to glimmer in its own glory.