Sastras point out that a jivatma is born repeatedly into this world because of ignorance about the true nature of the self. The greatest error that prevails is the ignorance which makes a jivatma identify the atma with the body mind complex. It thus fails to see itself as the essence of sat-chit-ananda and that it is not related to the kosas that envelop it, said Swami Paramartananda in a discourse.
Of the five kosas, the annamaya, the pranamaya, the manomaya, the vijnanamaya and the anandamaya, the most subtle is anandamaya, also known as karana sarira. This karana sarira is responsible for the gross and subtle bodies comprising the body mind complex in every jivatma. It is composed of ananda or bliss and is nearest to the blissful self. It refers to the ego. This state of bliss is recognised in deep sleep state when the senses and mind do not function, but still the causal body remains poised between the finite world and the blissful self.
Besides, the happiness that an individual experiences in the waking state is also owing to the causal body or karana sarira.
This is seen in the way one responds to the objects of the world as a source of joy and desires to possess them and then experiences the joy of them. It is known as the karana sarira because it is the source of ignorance and is constituted of ajnana and Avidya.
This ignorance is something that cannot be explained and is held to be beginningless.
It is because of this that we are able to know what we assume to be objective or empirical knowledge; and we also have the idea that we are ignorant about the Supreme Truth.
But though the origin of ignorance is untraced, it is shown to have an end when one realises the identity of the “I” as having no relation with the body.
