Song and dance
At Tsinghua University, in northwestern Beijing, a rising moon is reflected on the campus lake. From across a sea of water lilies, ghostly music comes drifting through the weeping willows. Its source is the square behind a Qing dynasty-style pavilion at the water's edge, where a mass of waltzing couples revolve to the music of a Chinese ballad.
The landscaped grounds of the capital's most prestigious seat of learning form a more pleasant surrounding than most. But across the city, the scene is repeated all summer in every park, and even in the public places at the centre of housing estates. Local residents come to dance, or simply to socialise and enjoy the music and night air.
Zhang Liyang is typical. The factory worker has come here every night since May, when the weather became warm enough for open-air dancing. She likes to waltz, rumba and tango. 'I only knew a few steps at first,' she says. 'I learned the rest from practising with my friends here.' As she finishes, a comfortably dressed, grey-haired man emerges from the throng. Smiling gently, he extends both arms and leads her onto the floor.
Across the square, Wu Yingli leaves the floor and returns to her group of retirees idling around a flask of oolong tea. Since retiring from her job at the university refectory, she has continued to live on campus. 'Dancing is the best way for me to exercise,' she says. 'The atmosphere here makes me feel happy, and that's important for people at my age, to keep going.' Tsinghua generously allows outsiders to enjoy its gardens, and lays on the lighting and music - piped through speakers hung on the pavilion's pillars.
Some young married couples take part, and even children, but most are past working age. To a western observer, it is a marvel how pensioners in the mainland manage to have such an active social life, with so little money. In large cities in Europe and the United States, parks are considered too dangerous to enter at night, and the old lock themselves indoors.
Most of the dancers spent their youth amid the chaos and even anarchy of the Mao Zedong era. But here, the lyrical music and courtly, ritualised nature of the proceedings speaks of a milder, more civilised time than the present, with its rave parties and casual relationships. With the sexual revolution unfolding at full tilt in China's cities, will these open-air summer dances be so widespread two decades hence?
In the square beside the lake, Ms Zhang's partner gives her a last twirl before the music fades and the lights flick off at 10pm. Those left begin to drift homewards, but they will return every night until the chill of autumn brings an end to this year's open-air dancing.