The story is told of St Francis, soon after the founding of his Order, that he was unsure what exactly to do next. So he he took advice from some trusted friends, and together they prayed about it. And the answer seemed to be that through Francis and his companions God wanted the world to hear the Gospel and be transformed. So Francis decided on a career of preaching and with two brothers set off without a plan and without provisions – taking fairly literally Jesus’ injunction to the disciples when he sent them out in pairs to announce the good news of the kingdom. And he preached. But Francis’ first recorded sermon was not in a church, not even in a village but by the side of the road, and to a congregation of swallows.

Francis’s official biographer, Thomas of Celano, describes the scene – moving amongst the flock of birds who had flown down from the trees and gathered around him, Francis reminded them how fortunate they were. Echoing Jesus, Francis told the birds, ‘You don’t till the earth or sow and reap a harvest, and yet God your Creator gives you everything you need: a coat of feathers, the joy and freedom of flight - the Earth itself to feed you and trees for shelter and protection. But beware’, Francis told his congregation, ‘beware the sin of ingratitude, praise God through your singing and study the goodness of God in the rhythm of the seasons and the beauty of creation’. And after receiving the sign of the cross they rose up singing and flew off in four directions, making the sign of the cross themselves in their flight. And from that day on Francis made it his habit to talk to the birds – and fish and rabbits and wolves and earthworms – and they listened quietly and did what he told them.

This pretty much is the picture most of us have of St Francis today, a fairytale image of an otherworldly saint, a hippie seven hundred years before hippies were invented, making daisy chains and talking to the birds. Charming and picturesque, but not very useful for 21st century Christians trying to live in the real world. The real Francis, I suggest, was less romantic. He’s also a lot more helpful to 21st century Christians who wonder what all this stuff about climate change and ecology has got to do with God.

Certainly Francis did talk to the birds – and the grass and the flowers and the earthworms – addressing them as brother and sister and exhorting them to praise God by running and jumping, and stretching and flying, and growing and chewing, praising God in their own way as we human beings do in ours. Francis also practised a fairly extreme version of voluntary poverty, living and working among lepers and the poorest of the poor. The spirituality of Francis was not an otherworldly or romantic spirituality but a spirituality of compassion and self-limitation, not a spirituality of solitary contemplation, but an earthy spirituality of joyful presence in the everyday, of celebrating the creation that he saw as an expression of God’s exuberant goodness and beauty refracted as through a stained glass window into a myriad of images.

Francis died young, and in considerable pain from the multiple illnesses that plagued the lower classes of his day. He lost control of the order he had founded, and even before he died his friars started the great squabble over his legacy that almost split the Franciscan order in two. But in the last year of his life, virtually blind and in pain, Francis composed the great poem that more than anything sums up his theology, one of the few surviving fragments of Francis’ own writing, the Canticle of Creation - on which our first hymn this morning was based. The poem expresses Francis’ awareness of kinship, of experiencing a family relationship with all things, because all things, all living things and even inanimate objects, are expressions of the overflowing love of God.

The great Franciscan theologian, Bonaventure, gives theological structure to what Francis saw intuitively – the Word of God is both what creates something out of nothing and what takes on human flesh in the form of Jesus Christ. The Word as God’s self-communication is literally God giving Godself away in the act of creation, which means the material universe is not something separate from God, but the outward expression of God – not just a bewildering array of stars and planets, rocks and mud and bacteria – but a unique, expanding, evolving expression of the infinitely self-expressive Word of God.

Francis understood that, seeing the whole of creation as a sort of book, the Word of God written in the alphabet of created things. Francis knew that because Jesus the Word of God takes on our physical form then we are physically related to God, to one another and to every living and non-living created thing. As a more contemporary theologian puts it, the physical substance of our lives – our bodies, but also the physical things we need to stay alive, the food we eat, the clothes we wear and the houses we live in – all that physicality is a kind of shared space in which our lives get intermingled and swapped around with everybody and everything else. Whether we like it or not we can’t keep ourselves separate from one another – and so in the Eucharist we acknowledge that by sharing a piece of bread and a cup of wine just as, for example, we constantly breathe and re-breathe the same air, and in doing that we recognise that our lives are interconnected. By being re-connected to our divine origin in Christ, we find ourselves connected to all of creation as brothers and sisters, and at the same time start to tune in to the fact that creation is speaking to us of Christ.

Because he saw the whole of creation as a sacramental expression of God’s self-giving love, Francis understood that he himself was connected in a family relationship to everything that is. Nothing exists separately; everything is interconnected and derives its identity from its relationship to everything else. At the most fundamental level, what we call our "self" is made up not just of the sum of our relationships but also the sum of our shared physicality.

That last bit, of course, isn’t just theology, it’s also science. It’s certainly how ecologists see reality, and it’s also what the impenetrable language of quantum physics tells us. It’s also what psychology and Christian spirituality also tell us – when human beings try to live without recognising or attending to our relationships with others, or our connection to our physical environment, we make ourselves deeply unhappy and generally sick.

Well, so what? If we do start seeing ourselves, not just as spending time down here on earth waiting to meet God up in heaven, but as interwoven and inextricably connected with a creation that in every breath exudes the Spirit of God, then so what? What difference does it make to how we live?

It makes a difference because we start to see ourselves as being in a sort of family relationship with everything around us. We begin to realise that it’s not just short-sighted to pump greenhouse gases into the air, or to fail to take action while waterways die and species are driven to extinction, it’s not just that failing to take action to prevent rising global temperatures and sea-levels puts future generations at risk – all the true things that climate change scientists keep telling us even though most of us have stopped listening – but that to live in a way that wounds God’s creation also wounds us - and wounds God. To allow species to become extinct at a faster rate than ever before in the life of our planet is an act of irreverence, because every created thing is a unique self-expression of God. For every species that vanishes there is a loss of divine possibility, forever.

It makes a difference because if we follow the theology of St Francis we see the value of ecosystems, rivers and wetlands, forests and wilderness areas and all living things not just in terms of how useful they are to human industry, tourism, or even medical science – not as resources on which we can place a dollar value, but as unique moments of the creative self-expression of God. And we begin to see ourselves as a bridge, as a part of creation made aware of its divine origins and so as a connection between creation and God – as catalysts for what St Paul in his letter to the Romans describes as the great work of the whole cosmos, growing and yearning towards its fulfilment in Christ.