A poem by William Blake (1757-1827).

The Jerusalem of the title does not refer to the city itself, but in the Christian imagery of the time meant a perfect place governed according to the principles of love and mercy. Blake vividly contrasts this hypothetical state to England as it was in his day, during the Industrial Revolution. In this period, the "green and pleasant land" was pockmarked with mills and other industrial buildings. These buildings must have looked pretty horrible: belching forth acrid black smoke, lit by the unholy red glow of the furnaces, and filled with the poor workers. To Blake these facilities were Hell on Earth, the antithesis of his Jerusalem. The second verse is a call to arms, both physical and mental, to right the injustices of the day and build the perfect caring society. It is more of an incitement to reform than a hymn to God, although the concept of Christ's mythical visit to England is used as a spur.

Here it is.

And did those feet in ancient time,
Walk upon England's mountains green?
And was the Holy Lamb of God
On England's pleasant pastures seen?
And did the countenance divine
Shine forth upon our clouded hills?
And was Jerusalem builded here
Among these dark satanic mills.

Bring me my bow of burning gold!
Bring me my arrows of desire!
Bring me my spear! O clouds unfold!
Bring me my chariot of fire!
I will not cease from mental fight
Nor shall my sword sleep in my hand
Till we have built Jerusalem
In England's green and pleasant land.

The poem is best known for its setting as a hymn by Charles Hubert Hastings Parry (1848-1918). This is the stirring anthem of the Women's Institute and is also sung every year at The Last Night of the Proms. It is regarded one of the British patriotic songs. For my money it is also the best.

It is not really about how great the country is (like "Land of Hope and Glory" or "Scotland the Brave"), how enduring it's institutions (like "God Save the Queen"), or how great its people are (like "Rule, Britannia!" or "Men of Harlech"). These are themes are common to most such songs across the world, and are better categorised as nationalist (or even jingoistic) than patriotic.

This one is about the problems it faces, and how no one should rest 'till they've all been put right. And the tune and arrangement kick ass, too.

I'm told (by tongpoo) that when sung in Northfield Mount Hermon School, USA, the last line is often replaced with "In every green and pleasant land".