A City Guide To Yaocheng for Social and political practices, therefore, are seldom if ever replicable. Comparative studies between different people, different countries, or the same country at different times can be very enlightening. But they fail to duplicate the precise experimental conditions of the natural sciences. Humans learn from history and from each other. Hence repeated observations of social reality are not observations of exactly the same reality. The actors involved have in all likelihood thought about themselves and their world in the meantime and have developed or otherwise changed their behavior or conditions as a result. Experimental observation allows for the construction of scientific theory because the objects of study, being either biological or mechanical, operate in relatively fixedpatterns andd isplay regularities according to ascertainable physical laws. A City Guide To Yaocheng 2016.