"A new command I give you: Love one another. AS I HAVE LOVED YOU, SO YOU MUST LOVE ONE ANOTHER. By this everyone will know that you are my disciples, if you love one another." (John 13:34-35)
How did Jesus love his disciples and why did he love them? Their natural qualities could not attract him. There was an infinite distance between them and him. He was knowledge, infinite Wisdom, they were poor fishermen, ignorant and filled with earthly thoughts. Yet Jesus calls them his friends, his brothers (cf. John 15:15). He wants them to reign with him in the kingdom of his Father, and to open this kingdom to them, he wants to die on the cross, for he said: "Greater love has no one than this: to lay down one’s life for one’s friends." (John 15:13)
When the Lord commanded his people to love their neighbor as themselves (cf. Lev 19:18), He was not yet on earth. He well knew how much a person loves himself and could therefore not ask his creatures for greater love for their neighbor. But when Jesus gave his apostles a new command, HIS COMMAND (cf. John 15:12), as he continues to say, he no longer speaks of loving one’s neighbor as oneself, but as He, Jesus, loved, as he will love until the end of time...
Lord, I know that you do not command anything impossible. You know my weakness, my imperfection, better than I do; you know that I could never love my sisters as you love them, unless you yourself, Jesus, did not love them in me. Because you wanted to grant me this grace, you gave new commandment. - How I love it! It gives me the assurance that it is your will to love in me all those you command me to love!... Yes, I feel it, when I show love, it is Jesus who acts in me.
(Autobiographical writings, Vimperk 1991, p. 214-215)