In plain words
In the same way the Avatāras come to teach the sādhana suited to the conditions of the time in each of the four yugas: dhyāna in the Kṛta Yuga, yajña in the Tretā Yuga, arcana in the Dvāpara Yuga, nāmasmaraṇa in the Kali Yuga. But in all these sādhanas there is the one Prema. In the same way, in the nine kinds of Bhakti too there is Prema alone! Śravaṇaṃ, kīrtanaṃ, Viṣṇu smaraṇaṃ, pāda sevanaṃ, vandanaṃ, arcanaṃ, dāsyaṃ, snehaṃ, ātma nivedanaṃ: these are the nine paths of Bhakti. In these nine paths, with nine flavours and nine sweetnesses, there is only the one Name of God! So however many paths of sādhana people may have, if they are not filled with Prema they are all simply in vain. So in every circumstance we must see that this principle of Prema does not change.
Such was the faith of Dharmarāja, eldest of the Pāṇḍavas! When he lived in the dense forests, when he ruled as emperor, when they dishonoured Draupadī, when they took Abhimanyu's life, when they cut the throats of the Upapāṇḍavas, in every circumstance he kept his mind firm and the same. Believing that no one but Kṛṣṇa could protect him, at all times he thought of nothing but the Name of Kṛṣṇa. No one ever saw Dharmaja swell with pride like an ordinary man, or sink because he had lost at dice. To have such an unwavering mind and an undeluded vision was the goal of the Pāṇḍavas' sādhana. Under the influence of Kali, to revile God when hardship, sorrow and loss befall, and to praise God when happiness, joy and health come: this has become the mark of the ordinary man today. This is not right. We must be equal-minded in joy and sorrow and attain the principle of Prema. We must believe, ‘The Lord of all, who is in all, is One!’
Here is a fine comparison for this. We have a body, don't we! In this body there are many limbs. Whichever limb suffers, the whole body feels the pain. If a tooth aches, the body feels the toothache itself, since the tooth is not other than itself. In the same way, if a leg aches, it feels the pain itself, since the leg is not other than itself.