In Physics, knowledge is acquired through the process of scientific investigations. Experimental facts about the observed phenomena are correlated and a mathematical model theory is worked out. Eventually, for the benefit of the non-physicists, a model/theory, in ordinary language, interpreting the mathematical scheme is formulated. Very often, the theories have to be modified or sometimes even dropped altogether, if the experimental evidences continue to contradict the model/theory. Abstraction is a crucial feature of the whole process and consists a map of reality. This can represent only some features of reality; and is very much ambiguous and inaccurate, having many contradictory meanings. The realization that all models and theories are approximate is basic to modern science. They can never explain all the aspects of reality, and will, therefore, never give a complete description of the real situation.