When the mind attains union with Śrī Bhagavān’s names, qualities, pastimes and so on, that is called smaraṇa.
Meditating on Śrī Hari is by nature the very life of all sādhana.

Still, in practicing the smaraṇa limb of bhakti, concentration of the mind is the absolute necessity.
If the mind is not pure, concentration is not possible.

The import is that if impurities in the form of the appearance of other things in the mind are not expelled, the heart and mind do not become clear. For this reason, the practice of smaraṇa is not possible for everyone.

Therefore, Śrī Jīva Gosvāmipāda has written, atha śaraṇāpattyādibhiḥ śuddhāntaḥkaraṇaś cet… nāmakīrtanāparityāgena smaraṇaṁ kuryāt.

“When the heart and mind have been purified by taking shelter of the Lord and other practices, the practice of smaraṇāṅga-bhakti should be performed along with nāma-kīrtana.”

The meaning is that as much as the sādhaka’s heart and mind are sanctified or cleansed by practicing the limbs of bhajana, such as having faith, taking shelter, service to Śrī Guru and the Vaiṣṇavas, hearing, chanting and so on, to that degree, smaraṇāṅga-bhajana gives happiness or enjoyment to the sādhaka.

Gradually, the sādhaka engaged in smaraṇa–sevā with great care and attention passes through several levels and finally arrives in the realm where love is attained.

Śrīmat Jīva Gosvāmipāda has mentioned those levels: tad idaṁ smaraṇaṁ pañca-vidhaṁ, yat-kiñcid anusandhānaṁ smaraṇam. sarvataś cittam ākṛṣya sāmānyākāreṇa manodhāraṇaṁ dhāraṇā. viśeṣato rūpādi-cintanaṁ dhyānam. amṛta-dhārāvad avicchinnaṁ tat dhruvānusmṛtiḥ. dhyeya-mātra-sphuraṇaṁ samādhir iti (Bhakti-Sandarbhaḥ 278 anuḥ).

“The aforementioned smaraṇa is of five kinds. Exploration of Śrī Hari’s name, form and so on to a small degree is called smaraṇa. Pulling one’s attention away from all sense objects and holding Śrī Hari’s form, qualities and so on steadily in one’s thoughts is called dhāraṇā. Contemplating his form and so on in a more specific way is called dhyāna. Uninterrupted remembrance, as though it were a stream of nectar, is called dhruvānusmṛti. When only that which is to be meditated upon appears in the mind, that is called samādhi.”

As a result of careful sevā of the smaraṇa limb of bhakti, the sādhaka is gradually blessed with the attainment of bhāva-samādhi, complete absorption in divine love.

Śrī Rādhākuṇḍa Mahānta Paṇḍita Śrī Ananta Dās Bābājī Mahārāja