Who likes it when they yell at him, when he is rude? No one, everyone takes offense, tears in their eyes. And when do you yell? Think about the fact that before you is not just an object of some kind, but a person who has a soul, mind, heart; enter into his life. But this can be done only when there is love for a person. If it does not exist, then one selfishness, self-love is obtained. The Lord said: "Let all be one", and prayed for this unity. And it can come true only in love. Without it, you can not reach the Kingdom of Heaven, because you can enter only by loving God. But if a person loves God, it means that he loves everything in general.
Imagine that a person is very generous. Then he gives to all, he does not share, because if he was generous for one, but for another there is no generosity. That's how love is. This is a property that is loved and loved by all. Therefore, the Lord said that the second commandment is like the first. If a man has learned to love God, he does not choose, he loves everything: both the tree and the insect, and even more so man, as the highest creation of God. Love is a method of knowing, because only by loving you can you know. Here someone loves, say, biology - and he recognizes it. And the other says: Oh, I do not like math. Hence, he has no idea about mathematics. So it is here. Why does a person not love God or why he does not love his neighbor? Yes, because he has no idea about God, he does not feel the other person either.