What does buck not understand the shock of the club?

Buck does not understand the shock of the club because he has been raised in a domesticated environment where he is accustomed to human care and comfort. The brutal reality of the wilderness and the harsh treatment from humans in the form of the club is foreign to him. This sudden shift from a safe, predictable life to one filled with violence and fear is overwhelming, leaving him confused and disoriented as he grApples with his instincts and the need for survival.