Now, suppose we go from this system to a much smaller system. So we decrease volume and we increase pressure but our temperature remains constant. So let's go back to this system, this system which was at standard temperature and pressure, these two values our distance between any two molecules was much larger than the distance or the size of the actual molecule itself. So that means we can use the kinetic theory to approximate how this behaves. Because if the distance is far then we can assume the volume of the molecules to be very, very small. And since they're far away, we can assume they don't attract or repel each other.