The slogan "One country, two systems," which is supposed to describe the relationship between the Chinese mainland and the capitalist enclave of Hong Kong, has been the repository of hopes, dreams and more than a little confusion since it was first articulated in 1997.

The idea that the former colony would retain its essence after being returned to China invited scrutiny on two counts: defining that "essence" and clarifying what would happen if it ever clashed with China's own perceived imperatives.

The prospect of a clash has become more real in recent weeks as Hong Kong residents have participated in a poll on how to select their top leader, a ballot that, while not legally binding, is nonetheless angrily denounced by the mainland.