content: one of the sorcerers said : " that is the man in the moon . the cassia tree grows so luxuriantly that in the course of time it would overshadow all the moon 's radiance . therefore it has to be cut down once in every thousand years . " then they entered the spreading halls . the silver stories of the castle towered one above the other , and its walls and columns were all formed of liquid crystal . in the walls were cages and ponds , where fishes and birds moved as though alive . the whole moon - world seemed made of glass . while they were still looking about them on all sides the lady of the moon stepped up to them , clad in a white mantle and a rainbow - colored gown .
answer: the cassia tree grows so luxuriantly that in the course of time it would overshadow all the moon 's radiance .
question: why did the tree need to be cut down once in every thousand years ?
target: why did the tree need to be cut down once in every thousand years ?
references: why did the tree need to be cut down once in every thousand years ?