what is the significance of 12 in keeping quite?

The number twelve has a special significance because there are 12 digits in a clock and for twice the amount of time that makes up 12 hours,we keep on talking and engaging in some activity or the other. That moment when we hold our peace and keep still, not speak in any language would be an exotic moment. Everyone can talk or do things but to keep one's silence and to listen, not just to others but also to the music of the world around us that gets drowned in the cacophony of everyday life. Neruda probably chooses this number in order to emphasis upon keeping patience and letting the stillness sink in.