Hexi fortune telling

What do you mean by "middle earth in the sand", "flowing water", "willow tree" and "great stream" in fortune telling?

"Earth in the sand", "flowing water", "willow" and "brook" are four syllables of a Chinese character, which are the sparks generated by heavenly stems and earthly branches's collision and an important part of a Chinese character. No problem itself can be explained accurately. Each syllable has two branches corresponding to it, and your question can only be like this if there is nothing else to add.