There are two parts to the Self. The first is the lower Self, or ego, which consists of the temporary body, the five senses, changing thoughts and opinions. The second is the higher or true Self, and is the essential core of a person that is unchanging.
Yoga practitioners desire to connect with and know the true Self in order to distinguish that which is unchanging and spiritual from that which is temporary and physical. When an individual is connected with the Self through their yoga practice, they are able to recollect who they truly are.