The root word ‘bha’ in the names of shumbha and nishumbha means ‘light’. However, their light is not real like the light from the sun. It is merely reflected light. Just as Sun represents the self and light in astrological language, Moon represents the mind and reflected light. Sattva is another name for the mind.
Buddhi is the highest function of the mind. However, buddhi is not the same as the Self or Atman. shumbha is none other than ‘Asmita’ (sense of ‘I’ or ‘Me’), the pseudo-self that identifies the self with non-self, whereas nisumbha represents Mamata (sense of ‘Mine’), or the attachment to things that the false-self clings to through identification with other objects. nishumbha is the brother of shumbha and one follows the other closely. Where there is this sense of ‘I’ automatically there is a sense of ‘mine’ as an extension of the false sense of self-hood. That is why shumbha and nishumbha are inseparable brothers.