Day 12 is the Vajrasattva mantra. Vajrasattva is an archetypal bodhisattva, the colour of sunlight on snow. He is particularly associated with absolute purity, our innate purity. There is a spontaneous laughter: “ha ha ha”, this laughter is the realization that we have always been pure, the purity has just been covered up with life. When you chant the mantra you can feel your shortcomings and unskilful actions falling away from you, being purified by Vajrasattva, eventually leaving you with just your innate purity.