In plain words
Whatever work was to be done, Kṛṣṇa first. That is why the Pāṇḍavas won victory. The Kauravas were those who, rolling in mere physical wealth and riches, believed, That alone is what matters to us, that alone is eternal and true for us. They forgot Kṛṣṇa. They put their faith in the world. They brought utter ruin on themselves. So the Mahābhārata teaches us the difference between the Pāṇḍavas and the Kauravas, and how Kṛṣṇa's principle of help works. The Pāṇḍavas all held, God first, world next, I last. The Kauravas were not so. I first world next. Last God. So for those who have led their life with God before them, there is always victory. This is what Sañjaya told Dhṛtarāṣṭra. Dhṛtarāṣṭra!
Yatra yogeśvaraḥ kṛṣṇo yatra pārtho dhanurdharaḥ tatra śrīr vijayo bhūtir dhruvā nītir matir mama.
He said that where Kṛṣṇa, who is God, and Arjuna, who has full faith, are both together, there they win complete victory. God, and faith fit for God: both must be there. Even with God present, if you have no faith in God you cannot win victory. Victory is in God's keeping. So if we win God over to ourselves, victory will be right with us. Tyāgarāja too said it. Rāmā! If I have just the strength of Your grace, the nine planets will come into my hand, he said. If we win that one thing, Prema for God, we shall have won everything. What is everywhere is only one. That is Prema. So we must make a fitting effort to win such Prema, which is the foundation. The chief teaching in Kṛṣṇa's life is the principle of Prema itself.
Without this Prema we can understand nothing of the principle of Kṛṣṇa. He Himself is full of Prema. He is the One who gave everything to the world. It is only through such Prema that we must see Prema. This Prema is very hard. That is, firm. Very precious. Very brilliant. If we want to gain this diamond called Prema, if we want to shape this diamond called Prema in the right way, we must shape it with the diamond called Prema itself. Go to a man who cuts diamonds and watch: they cut this diamond only with a diamond; it cannot be done with any other knife. If there is any impurity in our Prema, we must remove that impurity only with that diamond of Prema. It is only through Prema that Prema can be gained. Prema cannot be gained in any way through hatred; through hatred only hatred comes to us.