(_a_) _Integration_: grouping together of certain _like_ units (such as atoms or molecules, living cells or individuals) into a whole, (_b_) _Differentiation_: certain parts (or functions) of the aggregated whole becoming _unlike_ each other or specialized, and (_c_) _Adjustment_: fitting of the aggregated and differentiated whole into its environment. 6. In the opposite process of Dissolution or Extinction the thing undergoes the same changes in the reverse order before it disappears as such. In other words, given a thing and its environment, the one has to adapt and adjust itself to the other, or cease to exist. Nothing survives, as an individual, which does not change. Like a picture in its setting, a thing has to _fit_ itself to its environment in order that it might survive for the best advantage of itself and its kind. Thus, the _fit_ lives and the _unfit_ dies[81]. As the Qur'an expresses it [Arabic: ʾanna l-ʾarḍa yariṯuhā ʿibādiya ṣ-ṣālihūn] "the Earth is inherited by only the fit among My creatures."[82] This applies not only to plants and animals, man and society, but also to inanimate or inorganic things, as the President of the British Association announced some years ago. A man, for example, has for his environment, the atmosphere of the place he inhabits, the society he lives in, the occupation he follows, the laws he obeys, etc. He can live long and happily only when the qualities of his body and mind befit him to that environment, _i.e._, when they enable him (to become [Arabic: salih]) to adapt himself continuously to the circumstances of his position. What, then, is the general nature of such qualities? You know that one of the best methods of Science is Measurement. No scientific knowledge is exact unless it enables you not only to distinguish one quality from another, but also to measure each quality or determine its degrees in some way or other. It is not sufficient to know hot from cold but the degrees of temperature must be measured by a thermometer.