From the Vatican Website (here):
JOHN PAUL I
Wednesday, 27 September 1978
"My God, with all my heart above all things I love You, infinite good and our eternal happiness, and for your sake I love my neighbour as myself and forgive offences received. Oh Lord, may I love you more and more". This is a very well-known prayer, embellished with biblical phrases. My mother taught it to me. I recite it several times a day even now, and I will try to explain it to you, word by word, as a parish catechist would do.
We are at Pope John's "third lamp of sanctification": charity. I love. In philosophy class the teacher would say to me: You know St Mark's bell tower? You do? That means that it has somehow, entered your mind: physically it has remained where it was, but within you it has imprinted almost an intellectual portrait of itself. Do you, on the other hand, love St Mark's bell tower? That means that portrait, from within, pushes you and bends you, almost carries you, makes you go in your mind towards the bell tower which is outside. In a word: to love means travelling, rushing with one's heart towards the object loved. The Imitation of Christ says: he who loves "currit, volat, laetatur", runs, flies and rejoices (The Imitation of Christ ,1.III, c. V, n. 4).
To love God is therefore a journeying with one's heart to God. A wonderful journey! When I was a boy, I was thrilled by the journeys described by Jules Verne ("Twenty Thousand Leagues Under The Sea", "From The Earth To The Moon", "Round The World In Eighty Days", etc). But the journeys of love for God are far more interesting. You read them in the lives of the Saints. St Vincent de Paul, whose feast we celebrate today, for example, is a giant of charity: he loved God more than a father and a mother, and he himself was a father for prisoners, sick people, orphans and the poor. St Peter Claver, dedicating himself entirely to God, used to sign: Peter, the slave of the negroes for ever.
The Journey also brings sacrifices, but these must not stop us. Jesus is on the cross: you want to kiss him? You cannot help bending over the cross and letting yourself be pricked by some thorns of the crown which is on the Lord's head (cf. St Francis de Sales Oeuvres, Annecy, t. XXI, p. 153). You cannot cut the figure of good St Peter, who had no difficulty in shouting "Long live Jesus" on Mount Tabor, where there was joy, but did not even let himself be seen beside Jesus at Mount Calvary, where there was risk and suffering (cf. Ibid.,140).
Love for God is also a mysterious journey: that is, I cannot start unless God takes the initiative first. "No one", Jesus said, "can come to me, unless the Father who sent me draws him" (Jn 6:44). St Augustine asked himself: but what about human freedom? God, however, who willed and constructed this freedom, knows how to respect it, though bringing hearts to the point he intended: "parum est voluntate, etiam voluptate traheris"; God draws you not only in a way that you yourself want, but even in such a way that you enjoy being drawn (St Augustine, Tractates on the Gospel of John, 26.4).
With all my heart. I stress, here, the adjective "all". Totalitarianism, in politics, is an ugly thing. In religion, on the contrary, a totalitarianism on our side towards God is a very good thing. It is written: "You shall love the Lord your God with all your heart, and with all your soul, and with all your might. And these words which I command you this day shall be upon your heart; and you shall teach them diligently to your children, and shall talk of them when you sit in your house, and when you walk by the way, and when you lie down, and when you rise. And you shall bind them as a sign upon your hand, and they shall be as frontlets between your eyes. And you shall write them on the doorposts of your house and on your gates" (Dt 6:5-9). That "all" repeated and applied insistently is really the banner of Christian maximalism. And it is right: God is too great, he deserves too much from us for us to be able to throw to him, as to a poor Lazarus, a few crumbs of our time and our heart. He is infinite good and will be our eternal happiness: money, pleasure, the fortunes of this world, compared with him, are just fragments of good and fleeting moments of happiness. It would not be wise to give so much of ourselves to these things and little of ourselves to Jesus.
Above everything else. Now we come to a direct comparison between God and man, between God and the world. It would not be right to say: "Either God or man". We must love "both God and man"; the latter, however, never more than God or against God or as much as God. In other words: love of God, though prevalent, is not exclusive. The Bible declares Jacob holy (Dn 3:35) and loved by God (Mal 1:2; Rom 9:13), it shows him working for seven years to win Rachel as his wife; "and they seemed to him but a few days because of the love he had for her" (Gen 29:20). Francis de Sales makes a little comment on these words: "Jacob", he writes, "loves Rachel with all his might, and he loves God with all his might; but he does not therefore love Rachel as God nor God as Rachel. He loves God as his God above all things and more than himself; he loves Rachel as his wife above all other women and as himself. He loves God with absolutely and superbly supreme love, and Rachel with supreme husbandly love; one love is not contrary to the other because love of Rachel does not violate the supreme advantages of love of God " (St. Francis de Sales, Oeuvres, t. V, p. 175).
And for your sake I love my neighbour. Here we are in the presence of two loves which are "twin brothers" and inseparable. It is easy to love some persons; difficult to love others; we do not find them likeable, they have offended us and hurt us; only if I love God in earnest can I love them as sons of God and because he asks me to. Jesus also established how to love one's neighbour: that is, not only with feeling, but with facts. This is the way, he said. I will ask you: I was hungry in the person of my humbler brothers, did you give me food? Did you visit me, when I was sick (cf. Mt 25:34 ff).
The catechism puts these and other words of the Bible in the double list of the seven corporal works of mercy and the seven spiritual ones. The list is not complete and it would be necessary to update it. Among the starving, for example, today, it is no longer a question just of this or that individual; there are whole peoples.
We all remember the great words of Pope Paul VI: "Today the peoples in hunger are making a dramatic appeal to the peoples blessed with abundance. The Church shudders at this cry of anguish and calls each one to give a loving response of charity to this brother's cry for help" (Paul VI, Populorum Progressio, 3). At this point justice is added to charity, because, Paul VI says also, "Private property does not constitute for anyone an absolute and unconditioned right. No one is justified in keeping for his exclusive use what he does not need, when others lack necessities" (Paul VI, Populorum Progressio, 23). Consequently "every exhausting armaments race becomes an intolerable scandal" (Paul VI, Populorum Progressio, 53).
In the light of these strong expressions it can be seen how far we—individuals and peoples—still are from loving others "as ourselves", as Jesus commanded.
Another commandment: I forgive offences received. It almost seems that the Lord gives precedence to this forgiveness over worship: "So if you are offering your gift at the altar, and there remember that your brother has something against you, leave your gift there before the altar and go; first be reconciled to your brother, and then come and offer your gift" (Mt 5:23-24).
The last words of the prayer are: Lord, may I love you more and more. Here, too, there is obedience to a commandment of God, who put thirst for progress in our hearts. From pile-dwellings, caves and the first huts we have passed to houses, apartment buildings and skyscrapers; from journeys on foot, on the back of a mule or of a camel, to coaches, trains and aeroplanes. And people desire to progress further with more and more rapid means of transport, reaching more and more distant goals. But to love God, we have seen, is also a journey: God wants it to be more and more intense and perfect. He said to all his followers: "You are the light of the world, the salt of the earth" (Mt 5:13-14); "You must be perfect, as your heavenly Father is perfect" (Mt 5:48). That means: to love God not a little, but so much; not to stop at the point at which we have arrived, but with his help, to progress in love.
h/t Terry at idle speculations.