Samadhi comes when the memory is purified, or devoid of qualities

Verse 43

स्मृतिपरिशुद्धौ स्वरूपशून्येवार्थमात्रनिर्भासा निर्वितर्का ॥४३॥

smr‌ti-pariśuddhau svarūpa-śūnyeva-arthamātra-nirbhāsā nirvitarkā ॥43॥

The Samadhi called without reasoning (comes) when the memory is purified, or devoid of qualities, expressing only the meaning (of the meditated object).

Verse 44

एतयैव सविचारा निर्विचारा च सूक्ष्मविषय व्याख्याता ॥४४॥

etayaiva savicārā nirvicārā ca sūkṣma-viṣaya vyākhyātā ॥44॥

By this process (the concentrations) with discrimination and without discrimination, whose objects are finer, are (also) explained.

When memory is completely cleansed and purified, mind too is purified.

Both cease to function as distinct entites ; a no-mind state is experienced, and consciousness alone manifests itself, shining unblemished without reflection of external objects. This is called nirvitarka samapatti.

Memory is the recollection of past thoughts and experiences. It is the storehouse of past impressions. Its knowledge is reflected knowledge. The sadhaka should be aware that memory has tremendous impact on intelligence. By perseverance in yoga practices and persistent self-discipline, new experiences surface.

These new experiences, free from the memories of the past, are fresh, direct and subjective. 

It either merges with consciousness or takes a back seat, giving predominance to new experiences and bringing

clarity in intelligence. 

For the average person memory is a past mind. For the enlightened man, memory is a present mind. As memory is purified, intelligence becomes illuminative and moves closer to the seer, losing its identity. This is nirvitarka samapatti.

Transformation of the consciousness by contemplation on subtle objects such as the ego (ahamkara) , intelligence (buddhi) or the elements.(sound, touch, sight, taste and smell) , or the qualities of luminosity, vibrancy and dormancy of nature, conditioned by space, time and causation, is savicara samapatti. 

Without these reflections it becomes nirvicara samapatti.

In nirvicara samapatti, the sadhaka experiences a state without verbal deliberation.

All the subtle objects reflected in savicara are extinguished. 

He is free from memory, free from past experiences, devoid of all past impressions.

This new state of contemplation is without cause and effect, place or time.

The inexpressible states of pure bliss (ananda) and pure self (Atman) rise to the surface and are experienced by the sadhaka

PATANJALI YOGA SUTRAS