to get it straight; to start to understand things properly; enlightenment dawns

hole; opening; orifice (of the human body); (fig.) key (to the solution of a problem)

the seven apertures of the human head: 2 eyes, 2 ears, 2 nostrils, 1 mouth

nine orifices of the human body (eyes, nostrils, ears, mouth, urethra, anus)

the mind; capacity for clear thinking