What is significance of arguments between john the savage and mustapha mond in chapter 16 and 17

The Controller's explanation of society provides a rational counterpoint to John's pre-modern values. The contrast between the Controller's description of the pre-modern world, carried over from Chapter 3, and the modern one is all the more horrifying for the thread of truth it contains. The pre-modern world he describes is one of hypocrisy, selfishness and violence. It's a world that demanded comfort and stability and accepted the easy solutions it was offered, even at the price of emotional and intellectual freedom.