i took a quick look round -- a look of horror that came near to panic -- calculating vainly ways of escape ; and then , realizing how helpless i was to achieve anything really effective , i crept back silently into the tent and lay down again upon my sandy mattress , first lowering the door-curtain to shut out the sight of the willows in the moonlight , and then burying my head as deeply as possible beneath the blankets to deaden the sound of the terrifying wind .