Are we searching for solid joys and lasting treasure? Do we know where to find them? How do we know if we possess them?
I first came across the words “solid joys and lasting treasure” in a hymn I sang in school when I was a teenager. They did not mean much to me at that point in time. It was just one of those hymns we sang during morning assembly, and the last verse happened to end with those words.
The hymn is written by a British (John Newton), and the composer is Austrian (Franz Joseph Haydn). The tune sounds like the German National Anthem but it is called Austrian Hymn (or Gott erhalte Franz den Kaiser). The words of the last verse are as follows:
“Savior, if of Zion’s city,
I through grace a member am,
Let the world deride or pity,
I will glory in Thy Name.
Fading is the worldling’s pleasure,
All his boasted pomp and show;
Solid joys and lasting treasure
None but Zion’s children know.”
In the New Testament the Daughter of Zion is the bride of Christ, also known as the Church, according to the writer of the book of Hebrews (Cf. Heb 12:22). So what are the solid joys and lasting treasure that are only known to the Church and the People of God?
The verse tells us that we become members of the Church through grace (1 Cor 15:10; Eph 2:8). As God’s people we should not be obsessed with worldly pleasures, but rather glory in the name of the Lord. Only then can we discover solid joys and lasting treasure. (Cf. Matt 6:20; Mark 10:21; Luke 12:33)
It is quite difficult for Christians to avoid being enticed and consumed by the pleasures of this world without having a good understanding of the differences between joy, happiness and pleasure.
According to Peter John Kreeft, professor of philosophy at Boston College and The King’s College: “Joy is more than happiness, just as happiness is more than pleasure. Pleasure is in the body. Happiness is in the mind and feelings. Joy is deep in the heart, the spirit, the center of the self. The way to pleasure is power and prudence. The way to happiness is moral goodness. The way to joy is sanctity, loving God with your whole heart and your neighbor as yourself.” 
Here is his testimony on how to find true joy: “Every time I have ever said yes to God with something even slightly approaching the whole of my soul, every time I have not only said ‘Thy will be done’ (Matt 6:10, 26:42; Luke 22:42; Acts 21:14) but meant it, loved it, longed for it—I have never failed to find joy and peace at that moment. In fact, to the precise extent that I have said it and meant it, to exactly that extent have I found joy. (…) There is a catch. It’s a big one, but a simple one: you have to really do it, not just think about it. To do it completely requires something we dislike very much: death. Not the death of the body. The body is not the obstacle. The ego is. Self-will is. We fear giving that up even more than we fear giving up our body to death—even though that ego, the thing St. Paul calls ‘the old man’ (Rom 6:6) in us, or the Adam in us (Cf. Rom 5:14; 1 Cor 15:22), is the cause of all our misery.” 
So how can we be sure that solid joys and lasting treasure can indeed be found? Has anyone ever found it? Let us take a look at the life of the hymn writer to get some inspiration.
The story of John Newton’s early life is generally quite well known. He was born on July 24, 1725, in London. His mother, a godly woman, died when he was not quite seven years of age. When he was eleven years old, he went to sea with his sea-captain father and followed this life for the next eighteen years. These years were filled with adventure but were one continuous round of rebellion and debauchery. He became known as one of the most vulgar and blasphemous of men and was involved with the slave trade for a number of years.
On 10th March 1748, the ship he was travelling on encountered a great storm. When the ship went plunging down into the trough of the sea few on board expected her to come up again. The hold was rapidly filling with water. As Newton hurried to his place at the pumps he said to the captain, “If this will not do, the Lord have mercy upon us!” His own words startled him. “Mercy!” he said to himself in astonishment, “Mercy! mercy! What mercy can there be for me? This was the first desire I had breathed for mercy for many years!” About six in the evening the hold was free from water, and then came a gleam of hope. “I thought I saw the hand of God displayed in our favour. I began to pray. I could not utter the prayer of faith. I could not draw near to a reconciled God and call him Father. My prayer for mercy was like the cry of the ravens, which yet the Lord does not disdain to hear.” “In the gospel,” says Newton, “I saw at least a peradventure of hope but on every other side I was surrounded with black, unfathomable despair.” On the peradventure of hope Newton staked everything. He sought mercy – and found it.
Following his dramatic conversion experience and his call later at the age of thirty-nine to the Christian ministry, Newton became pastor of the Anglican parish in the little village of Olney, near Cambridge, England, and began writing hymn texts that expressed his spiritual experiences and convictions. He was the author of many popular hymns, including “Amazing Grace” and “Glorious Things of Thee are Spoken”. The earlier is really a testimony of Newton’s early life and conversion. The latter shows Newton’s profound respect for the covenantal promises to the Jews as well as to the local church and its earthly ministry.
Reference : http://www.peterkreeft.com/topics/joy.htm
Here is one of Newton’s finest hymns, “Glorious Things of Thee Are Spoken” as performed by Light and Life Hour Choir