风可通亦可密，私语不可传；光可闭亦可透，情绵不可露。
Wind can be both open and dense,but whisper will not be let out;
light can be can also be close blacked out and let in,the felling can't be revealed.

全透光状态
Fully light-penetrating state

半透光状态        
Semi light-penetrating state

全闭光状态
Fully black-out state