Isaiah 40.12-17, 27-end; 2 Corinthians 13.11-end; Matthew 28.16-20

Almighty and everlasting God, you have given us your servants grace, by the confession of a true faith, to acknowledge the glory of the eternal Trinity and in the power of the divine majesty to worship the Unity: keep us steadfast in this faith, that we may evermore be defended from all adversities; through Jesus Christ our Lord. Amen.

BACK in 1987, preaching at Durham Cathedral, Canon Professor Dan Hardy said: "Let me be completely straightforward. Trinity Sunday is the most exciting day of the year, because it celebrates the simple heart of Christian faith, and wraps all the excitement of the other great festivals of the Church's year into one sunburst of a celebration. But there is also a sense in which this excitingly simple heart of the Christian faith is an open heart; and for that reason, it cannot be wrapped up."

More than 100 years earlier, also in Durham Cathedral, the Precentor encouraged the then rare practice of singing hymns. Not finding suitable music, he composed his own, and tried it out on Sunday afternoons with his family and others who gathered in the Galilee Chapel (the nave was a step too far).

And so it was there that the tune Nicaea, named after the credal faith, was matched to Bishop Heber's text, "Holy, holy, holy". With its rising thirds raising our hearts to heaven, John Bacchus Dykes etched his place in the story of hymnody, and gave the Church a hymn with which to celebrate Trinity Sunday.

As Dykes used his creativity to express his love for God, he reflected back God's creativity, which expresses his love for the world. I think of that convergence of creativity each February, when Dykes's grave is smothered in snowdrops: the first flowers of the New Year and, in their own way, fragile and beautiful signs of God's creative life.

Trinity is how God is: holy, glorious, creative, beautiful, life-giving: everything that is not isolated and static. Theologians talk of perichoresis, a word derived from "around", "make room for", and "dance", to describe God's Trinitarian life. Trinity Sunday is God's invitation to dance, and is, indeed, exciting.

So we hear today of the uncontrollability and unmeasurability of God's life: "Who has measured the waters in the hollow of God's hand?" asks Isaiah, "Who taught him knowledge?" Who indeed?

Paradoxically, Jesus's claim to have been given all authority in heaven and earth was made to a bedraggled and confused group of 11 disciples, who were not sure whether to doubt or to worship. His closest friends were unprepared to have an impossible commission entrusted to them. They were thrown on to what Paul, at the end of his sometimes painful correspondence with the Corinthians, described quite simply as the grace, love, and communion of God.

That grace had down-to-earth implications, and he told them to put things in order in their disordered church, to agree and live peacefully with each other. We who are made in the image of God are to live peacefully and steadfastly day by day as people who trust the God whom we confess. There are consequences for our living.

Having excoriated the attitude that the Church can go through "all those interminable Sundays after Trinity", as he once heard them described, as if nothing happened, Professor Hardy concluded his sermon:

We make a big mistake not connecting Trinity season with Advent, as far off as it is. The season of Trinity looks forward to Advent and the coming of the Last and Great Day, and so it should. There is hardly enough time during the many Sundays between now and Advent to complete the movement of God which has begun in us.

This Trinity Sunday, in a sunburst of celebration, we worship a holy God who invites us, with mutual excitement, to launch out into the dance of God's life throughout the coming days until Advent, guided this year by Matthew. Playfully, perhaps Lewis Carroll can have the last word about risking that leaping out:

"You can really have no notion how delightful it will be
When they take us up and throw us, with the lobsters, out to sea!"
"What matters it how far we go?" his scaly friend replied.
"There is another shore, you know, upon the other side.
The further off from England the nearer is to France -
Then turn not pale, beloved snail, but come and join the dance.
Will you, won't you, will you, won't you, won't you join the dance?"

Alice in Wonderland