Thursday night saw a glitzy premiere at Windsor Castle, complete with film stars on the red carpet. But rather than a Hollywood blockbuster or homegrown movie, this was the launch of a documentary by the King. Called Finding Harmony, it will be released next week. It is being promoted as the King’s vision for the planet, while the head of the king’s charity, the King’s Foundation, says it is about his philosophy of harmony.

While the documentary explores the King’s well-known love of nature and his thoughts on the future of the planet, his interest in the philosophy of harmony is perhaps not so well-known. Yet it is something that he has been mulling over for decades. A whole section of a two-volume set

But the idea of harmony owes its origins to ancient Greek and Christian thinking. In a speech he gave in 2015 in Louisville, Kentucky, Prince Charles urged people to develop joined-up thinking about interdependent relationships within nature. “The ancient Greek word for the process of joining things up was Harmonia”, he said, “so joined-up thinking needs to create harmony”.

This idea of harmony is evident in Plato’s work, The Timaeus, where he describes the cosmos as a collection of elements arranged in musical ratios and this internal harmony ensures its survival, while St Ambrose, one of the earliest Christian writers saw the creation of the world, described in the Book of Genesis, as a narrative about harmony with a balance between the elements. He saw the way voices are lifted in harmony as symbolising the greater harmony of God’s creation.

Someone else who, like the King, expressed concern at a lack of harmony in the way people live now, was Pope Francis. In his major work on the environment, Laudato Si, he warned that humanity’s arrogance in attempting to dominate planet Earth had upset the balance of creation. “The harmony between the Creator, humanity and creation as a whole was disrupted by our presuming to take the place of God and refusing to acknowledge our creaturely limitations”, he wrote.

In other words, if there is any chance of the joined-up thinking the King calls for in our relationship with one another and with nature, a starting point for harmony needs to be humility.