What is the mark of the ego?

The individual soul of the form of 'l' is the ego. The Self which is of the nature of intelligence
(chit) has no sense of l. Nor does the insentient body possess a sense of 'I'. The mysterious appearance of a delusive ego between the intelligent and the insentient, being the root cause of all these troubles, upon its destruction by whatever means, that which really exists will be seen as it is.
This is called Liberation (moksha).
 #SriRamanaMaharshi.