The older I get, the more convinced I become that the most important thing in life is to love and be loved.
Of course, it is important to be happy, and to make others happy, too. But happiness and love are really just two sides of the same coin. So, ultimately, it is all about loving and being loved.
If the quality of the love we give and receive is good, then our lives will be good too.
If the quality of the love we give and receive is bad, then - no matter how much we earn, or how high our status, or how much we achieve - our lives will be bad too.
The Bible expresses it nicely: "Better is a dinner of herbs where love is, than a stalled ox and hatred therewith." (Proverbs 15:17)
The quality of the love we give and receive - especially the love we give - is the subject of an uplifting little book called How To Love, published recently by Vietnamese Buddhist monk, teacher and writer Thich Nhat Hanh. Its deepest insight is that love - true love - requires understanding.
"Understanding is love's other name," he writes. "If you don't understand, you can't love."
It is possible to have intense feelings for someone- a partner, a friend, a parent, a child - and yet not know how to love them.
Intense feelings can be selfish, greedy and manipulative.
They can lead us to act in ways that are damaging to the very people we profess to love.
Thich Nhat Hanh writes: "Often, when we say, 'I love you' , we focus mostly on the idea of the 'I' who is doing the loving and less on the quality of love that is being offered."
That is where the danger lies.
TO LOVE IS TO UNDERSTAND
True love involves loving, kindness and compassion.
When we truly love someone, we want to help them.
We want to alleviate their suffering, calm their fears, meet their needs and bring them joy.
But we can help them only if we understand them.
And we can understand them only if we listen to them.
"To love someone, you have to understand the real needs of that person, and not impose on her what you think is needed for her to be happy," says Thich Nhat Hanh.
"Understanding is the foundation of love."
In his book, he advises us to practise the art of listening deeply, to ask our loved ones about their wishes, hopes, desires, difficulties and fears, and what would make them happy.
Just 10 minutes of listening with all of our hearts can help us to understand them - and therefore to love them - more deeply.
It sounds basic.
But how many of us, in the last week, month or year, have actually made the time to do it?
In Shakespeare's tragic play, Othello, the title character, after murdering his wife in a fit of jealous rage, describes himself as "one that loved not wisely but too well".
His love, though passionate and intense, was warped by jealousy and fear, and led only to suffering.
In our own small way, we can make the same big mistake.
We can focus too much on the intensity of the love we feel, and not enough on the quality of the love we give.
Thich Nhat Hanh's challenge to us is to learn to love both wisely and well.
•Gary Hayden is a philosophy and science writer.