Having lived with this questions for some forty years without yet finding the answers, the least one can do is to render an account of some of the vicissitudes met with along the way.

• 对这些问题研究了大约四十年，人们众说纷纭，仍然没有得出确切的答案，在此只好将多年来的研究成果和观念变化做一些列举和说明。