CC Madhya 7.99
vidāya karila tāre śakti sañcāriyā
After some time the Lord would embrace these people and bid them return home, having invested each of them with spiritual potency.
In his Amṛta-pravāha-bhāṣya, Śrīla Bhaktivinoda Ṭhākura explains that this spiritual potency is the essence of the pleasure potency and the knowledge potency. By these two potencies, one is empowered with devotional service. Lord Kṛṣṇa Himself or His representative, the unalloyed devotee, can mercifully bestow these combined potencies upon any man. Being thus endowed with such potencies, one can become an unalloyed devotee of the Lord. Anyone favored by Lord Śrī Caitanya Mahāprabhu was empowered with this bhakti-śakti. Thus the Lord’s followers were able to preach Kṛṣṇa consciousness by divine grace.