Don't go down the narrow back street.

不要走狭窄偏僻的街道。

The two congratulated  each other, first, then discussed each other's talks for a little while, then moved on to other,   broader philosophical topics, and then finally narrowed back in on the NewLife Technology and its  implications.

两人首先互相祝贺，然后讨论了一会儿对方的谈话，然后转向其他更广泛的哲学话题，最后回到新生命技术及其含义上。