As water flows from high to low, knowledge has always flowed from where there is more to where there is less. Those countries that are better at absorbing the knowledge inflow have been more successful in catching up with the more economically advanced nations. On the other side of the fence, those advanced nations that are good at controlling the outflow of core technologies have retained their technological leadership for longer. The technological 'arms race', between backward countries trying to acquire advanced foreign knowledge and the advanced countries trying to prevent its outflow has always been at the heart of the game of economic development.