天花乱坠

In the Southern and Northern Dynasties(420-589), in the reign of king Wu of Liang, there was a monk called Master Yun Guang who was a very accomplished（有技巧的） preacher. Once he explained the sutra（佛经，箴言） so proformdly and subtly that the God of Flowers was moved and sent divine（神圣的） flowers down to earth. Soon the land was covered with flowers.

This idiom was later used metaphorically to describe talking in a vivid and eloquent way(mostly in an exaggerated and impartical manner).