Chapter-1, Sutra 11

Patanjali Yogasutra 1.11

(Smriti)

अनुभूतविषयासंप्रमोषः स्मृतिः ॥ १.११॥

Memory is when the (vrittis of) perceived subjects do not slip away (and through impressions come back to Consciousness).

Memory is the mental modification that is caused by the retention of past experiences of objects, without adding anything from other sources. Memory can arise from direct perception, false knowledge, verbal delusion, and sleep. For example, you hear a word. That word is like a stone thrown into the lake of the mind, it causes a ripple, and that ripple rouses a series of ripples; this is memory. So in sleep, when the peculiar kind of ripple called sleep throws the mind into a ripple of memory, it is called a dream. Dream is another form of the ripple which in the waking state is called memory. 

Memory is one of the five types of vrittis, or fluctuations of the mind, that need to be controlled in order to achieve the state of yoga, or union with the Supreme Reality. Memory can be helpful or harmful, depending on the nature and quality of the impressions that are stored in the mind. Memory can lead to attachment, aversion, or ignorance, which are the root causes of suffering. Memory can also lead to Knowledge, detachment, power, and righteousness, which are the means of liberation. Memory can be influenced by the three gunas, or qualities of nature, which are sattva (purity), rajas (activity), and tamas (inertia). Memory can be purified, activated, or dulled by these gunas. Memory can be overcome by practice and non-attachment, which are the two main principles of yoga.

Similar comments are available in various Vedic texts, like:

Katha Upanishad:

यदा पञ्चावतिष्ठन्ते ज्ञानानि मनसा सह ।

बुद्धिश्च न विचेष्टते तामाहुः परमां गतिम् ॥

When the five types of knowledge are established in the mind along with the intellect, and the intellect does not waver, that they call the Highest State.

This verse is from one of the principal Upanishads that deal with the philosophy of yoga. It describes the state of samadhi, or the Superconscious State, where the mind is free from all vrittis and rests in the Self.

Mundaka Upanishad:

यथा नद्यः स्यन्दमानाः समुद्रे ऽस्तं गच्छन्ति नामरूपे विहाय । तथा विद्वान्नामरूपाद्विमुक्तः परात्परं पुरुषमुपैति दिव्यम् ॥

As the rivers flowing into the ocean lose their names and forms, so the wise one, freed from name and form, goes to the Supreme Person who is beyond all.

This verse is from the Mundaka Upanishad, which is another important Upanishad that teaches the doctrine of yoga. It compares the liberation of the soul from the bondage of the body and the world to the merging of the rivers into the ocean.

Yoga Vasistha:

योगवासिष्ठे चित्तवृत्तिनिरोधो नास्ति तत्र चित्तमेव निरोधः । चित्तं निरोधयति यः स निरोधः स चित्तं निरोधयति यः स योगः ॥

In Yoga there is no suppression of the modifications of the mind, there the mind itself is the suppression. He who suppresses the mind is the suppression, he who suppresses the mind is the yoga. 

This verse is from the Yoga Vasistha, which is a classic text of yoga that contains the teachings of Sage Vasistha to prince Rama. It presents a different perspective on the concept of nirodha, or cessation, which is the goal of yoga. It suggests that the mind itself is the cause and the effect of its own suppression, and that the realization of this fact is the essence of yoga.