During the picking season my grandmother would get out of bed at four o'clock ... and creak down to her knees and chant in a sleep-filled voice, "Our Father, thank you for letting me see this New Day. Thank you that you didn't allow the bed I lay on last night to be my cooling board, nor my blanket my winding sheet." In this excerpt use context clues to identify what comparison Angelou is making with the metaphors of bed as cooling board and blanket as winding sheet.