2. Christ says: "If anyone loves me, he will keep my word, and my Father will love him, and we will come to him..." (Jn 14:23). In the very centre of Christ's teaching lies the great commandment of love. This commandment was already inscribed in the Old Testament tradition, as today's first reading from the book of Deuteronomy testifies.

When the Lord Jesus answers the question of one of the scribes, he goes back to this writing of the divine Law, revealed in the Old Covenant: "Which is the first of all the commandments!" "The first is... You shall love ... the Lord your God with all your heart, with all your mind, and with all your strength." "And the second is this. Thou shalt love thy neighbour as thyself." "There is no other commandment more important than these" (Mk 12:29-31).

3. That interlocutor, who was evoked by St. Mark, accepted Christ's answer with reflection. He accepted it with profound approval. It is necessary for us too, today, to reflect briefly on this 'greatest commandment', in order to accept it again with full approval and deep conviction. First of all, Christ propagates the primacy of love in man's life and vocation. Man's greatest vocation is the call to love. Love also gives the ultimate meaning to human life. It is the essential condition of man's dignity, the proof of the nobility of his soul. St Paul will say that it is "the bond of perfection" (Col 3:14). It is the greatest thing in man's life, because true love carries within itself the dimension of eternity. It is immortal: "charity will never end" we read in the First Letter to the Corinthians (1 Cor 13:8). Man dies as far as the body is concerned, because such is the destiny of everyone on earth, but this death does not harm the love that has matured in his life. Of course, it remains above all to bear witness to man before God, who is love. It designates man's place in the Kingdom of God; in the order of the Communion of Saints. The Lord Jesus to his interlocutor in today's Gospel - seeing that he understands the primacy of love among the commandments - says: "You are not far from the kingdom of God) (Mk 12:34).

4. There are two commandments of love - as the Master expressly states in his reply - but love is one. One and identical embraces God and neighbour. God: above all things, for he is above all things. The neighbour: with the measure of man, and therefore 'as himself'.

These 'two loves' are so closely connected that one cannot exist without the other. St John says it elsewhere: 'For whoever does not love his brother whom he sees, cannot love God whom he does not see' (1 John 4:20). Therefore, one love cannot be separated from the other. True love of man, of one's neighbour, therefore, which is true love, is at the same time love of God. This may astonish some. It certainly astonishes. When the Lord Jesus presents his listeners with the vision of the last judgement, reported in St Matthew's Gospel, he says: "I was hungry and you gave me food, I was thirsty and you gave me drink; I was a stranger and you welcomed me, naked and you clothed me, sick and you visited me, in prison and you came to visit me" (Matthew 25:35-36).

Then those who hear these words are amazed, for we hear them ask: "Lord, when did we ever do all this to you?". And the answer: 'Truly I say to you, whenever you have done these things to one of the least of these brothers - that is, to your neighbour: to one of men - you have done it to me' (cf. Mt 25:37, 40).

5. This truth is very important for our whole life and behaviour. It is especially important for those who try to love men, but "do not know whether they love God" or even claim not to "know" how to love Him.

This difficulty is easy to explain when one takes into consideration man's entire nature, his entire psychology. It is, in a way, easier for man to love what he sees than what he does not see (cf. 1Jn 4:20).

6. Yet man is called and is called with great firmness, the words of the Lord Jesus testify to this, to love God, to the love that is above all things. If we reflect on this commandment, on the meaning of the words already written in the Old Testament and repeated with such determination by Christ, we must recognise that they tell us much about man himself. They reveal the deepest and, at the same time, definitive perspective of his being, of his humanity. If Christ assigns to man as a task such love, that is, the love of God that he, man, does not see, this means that the human heart conceals within itself the capacity for this love, that the human heart is created 'to measure this love'. Is this not the first truth about man, that he is the image and likeness of God himself? Does not St Augustine speak of the human heart remaining restless until it rests in God? So then, the commandment to love God above all things reveals a scale of man's inner possibilities. This is not an abstract scale. It has been reconfirmed and is constantly being confirmed by all men who take their faith, the fact that they are Christians, seriously. Yet there is no shortage of men who have heroically confirmed this scale of man's inner possibilities.

[Pope John Paul II, homily 4 November 1979]