The source of all types of sorrow is ignorance (ajnana). The source of ignorance is identification with the body - the delusion that you are the body. This can be removed only by the acquisition of right knowledge. To remove darkness, light is needed; darkness cannot be frightened away, nor can you make it yield by prayer or petition or protest. It will not disappear unless light comes in. When ignorance goes, grief too vanishes. That is why, in the Geeta, Lord Krishna tells Arjuna, “Attach yourself to Me and earn the light of True Knowledge and tread the path of ‘No grief’.”(Geetha Vahini, Chap 14.)