The mark at the middle of two eyebrows symbolises opening of third eye (spiritual eye) which implies enlightenment. The three lines on the forehead symbolise the gross body, subtle body and causal body that are reduced to ashes when the third eye opens and enlightenment happens. These words may sound like something dramatic takes place when enlightenment happens but the fact is that if the process of Self Inquiry is followed to attain enlightenment, the changes take place gradually. It is not that all changes take place during direct realisation. Also, changes continue to take place after enlightenment as unconscious mind takes time to change.