TRANSLATION
"By regularly rendering devotional service, one gradually becomes attached to the Supreme Personality of Godhead. When that attachment is intensified, it becomes love of Godhead.
PURPORT
Bhakti-rasāmṛta-sindhu (1.2.2) gives the following information about sādhana-bhakti:
kṛti-sādhyā bhavet sādhya-
bhāvā sā sādhanābhidhā
nitya-siddhasya bhāvasya
prākaṭyaṁ hṛdi sādhyatā
The process of devotional service-beginning with chanting and hearing-is called sādhana-bhakti. This includes the regulative principles that are intended to awaken one to devotional service. Devotional service is always dormant in everyone's heart, and by the offenseless chanting of the holy names of the Lord, one's original dormant Kṛṣṇa consciousness is awakened. This awakening to Kṛṣṇa consciousness is the beginning of sādhana-bhakti. This can be divided into many different parts, including faith, association with devotees, initiation by the spiritual master, engagement in devotional service under the instructions of a spiritual master, steadiness in devotional service and the awakening of a taste for devotional service. In this way, one can become attached to Kṛṣṇa and His service, and when this attachment is intensified, it results in ecstatic love for Kṛṣṇa. The word rati is explained in the Bhakti-rasāmṛta-sindhu (1.3.41) as follows:
vyaktaṁ masṛṇatevāntar-
lakṣyate rati-lakṣaṇam
mumukṣu-prabhṛtīnāṁ ced
bhaved eṣā ratir na hi
"When a tenderness of the heart is manifest, there is rati, or attachment. Those who are interested in being liberated from material bondage must manifest this tenderness called rati." This attachment is not like material attachment. When one is liberated from material contamination, the awakening of attachment for Kṛṣṇa's service is called rati. In the material world there is attachment for material enjoyment, but this is not rati. Transcendental rati can be awakened only on the spiritual platform. Ecstatic love for Kṛṣṇa (prema) is described in the Bhakti-rasāmṛta-sindhu (1.41) as follows:
samyaṅ masṛṇita-svānto
mamatvātiśayāṅkitaḥ
bhāvaḥ sa eva sāndrātmā
budhaiḥ premā nigadyate
"When the heart is completely softened and devoid of all material desires and when one's emotional feelings become very strong, one becomes very much attached to Kṛṣṇa. Such purified emotion is known as pure love."