6. The various sciences in their serial development develop the whole art of Method. Mathematics develops abstraction, deduction, and definition; Astronomy abstraction, deduction, and observation; Physics adds experiment; Chemistry adds nomenclature; Biology adds classification, and for the first time brings into prominence the important notion of _conditions of existence_, and the variation of phenomena under varying conditions: so that the relation of the organism to its medium is one never to be left out of sight. In Biology also clearly emerges for the first time what I regard as the true notion of causality, namely, the _procession_ of causes,--the combination of factors in the product, and not an _ab extra_ determination of the product. In Vitality and Sensibility we are made aware that the causes are _in_ and not _outside_ the organism; that the organic effect is the organic cause in operation; that there is autonomy but no autocracy; the effect issues as a resultant of the co-operating conditions. In Sociology, finally, we see brought into prominence the _historical conditions of existence_. From the due appreciation of the conditions of existence, material and historical, we seize the true significance of the principle of Relativity. 7. Having thus indicated the series of the abstract sciences we have now to consider more closely the character of Biology. The term was proposed independently yet simultaneously in Germany and France, in the year 1802, by Treviranus and Lamarck, to express “the study of the forms and phenomena of Life, the conditions and laws by which these exist, and the causes which produce them.” Yet only of late years has it gained general acceptance in France and England. The term Cosmology, for what are usually called the Physical Sciences, has not yet come into general use, although its appropriateness must eventually secure its recognition. Biology,--the abstract science of Life,--embracing the whole organic world, includes Vegetality, Animality, and Humanity; the biological sciences are Phytology, Zoölogy, and Anthropology. Each of the sciences has its cardinal divisions, statical and dynamical, namely, Morphology--the science of form,--and Physiology--the science of function. Morphology embraces--1°, _Anatomy_, i. e. the description of the parts then and there present in the organism; and these parts, or organs, are further described by the enumeration of their constituent tissues and elements; and of these again the proximate principles, so far as they can be isolated without chemical decomposition. 2°, _Organogeny_, i. e. the history of the evolution of organs and tissues.