At another time and place (Mt. 22:35-40), Jesus spoke of the two greatest commandments: "You shall love the Lord your God with all your heart, and with all your soul, and with all your mind. This is the great and first commandment. And a second is like it, You shall love your neighbor as yourself. On these two commandments depend all the law and the prophets."
Those two commandments summarized the entire Old Covenant (the Old Testament). But Jesus established a new and everlasting covenant in his blood (the New Testament). And with a new covenant came a new commandment.
The first commandment remains: "You shall love the Lord your God with all your heart, and with all your soul, and with all your mind". But now that first commandment has a new context. God now has a human face, the face of Jesus Christ.
The second commandment has changed, however. You shall no longer love your neighbor as yourself. That's not good enough, not for the disciple. For the disciple, the commandment now is, "Love one another (not as you love yourself), but as I have loved you." That's Jesus' commandment to us in today's Gospel passage (Jn. 15-9-17). "As the Father loves me, so I also love you... love one another as I love you."
Now, that's a tall order. As much as God has loved himself (the Father loving the Son), the Son has loved us. And we're called to do likewise with one another. The humble heart acknowledges its own limitations and recognizes the impossibility of doing as Jesus commanded from a human perspective. God is the very source of eternal and perfect love. It's impossible for any mortal creature to love to a degree that matches God's.... unless it is God himself who is the source of love within each of us. If God is the agent of love within us, only then can we fulfill the command of Jesus to love.
The good news is that the sacraments precisely give us this power. The sacraments make us one in Jesus, to the extent that Jesus identified himself with his Church (Acts (9:4). When the sacraments truly transform us, we can then say, with Saint Paul: "I have been crucified with Christ; it is no longer I who live, but Christ who lives in me; and the life I now live in the flesh I live by faith in the Son of God, who loved and gave himself for me (Gal. 2:20)."
When it is Jesus who lives in us, it is Jesus who loves within us. Then we can respond to his command: "Love one another as I have loved you." God bless you.
Bartolomé Esteban Perez Murillo, The Two Trinities [retrieved from https://commons.wikimedia.org/wiki/File:Bartolomé_Esteban_Perez_Murillo_003.jpg]