In this state of
Samadhi the mind continues to function. But it is completely absorbed in the particular object contemplated. The duality of the subject and the object still remains. Therefore, this stage is also called Savitarka (contemplative / reflective) Samadhi.
In the advancement of this stage, the knowledge of that particular object contemplated also slowly fades away and the yogi becomes aware of the inner apparatus of cognition only. He experiences supreme bliss, which is why this state is also known as Sananda Samadhi.