The path of life on Earth is like a flowing river--some species get caught in a sinkhole and disappear for ever, while others float stably along and barely change in form for hundreds of millions of years. But the rhododendrons are swept by a rushing torrent, ever changing, so excitedly caught up in the evolutionary process that they are unable to settle down.
地球生命一路走來，如那流動的河水，有些物種在過程中如進深潭，就此消失；有些則穩穩流來，上億年來形態不變；杜鵑如急湍，變化多，興奮的在衍化過程中定不下來，也因此讓人難以捉摸。