Confused: It looks as if the main task for black is to die nicely, so that white can't live. forces , otherwise Black would live with . then destroys the potential white eye at a. From now on, White can only watch the group die at Black's leisure.
If White takes with , Black retakes immediately with . Should White want to go on with , the eyespace will be too small for White to live.
White is left with a Rabbitty Six group, which is dead once the vital point at is filled.
ChrisSchack: Just to tidy up, 2 makes an eye in gote, then 3 lives in the corner, removing any space for a second eye.