insuperable difficulty in the notion that at some period in the evolution of humanity this divine spark [the soul] may have acquired sufficient concentration and steadiness to survive the wreck of material forms and endure forever. Such a crowning wonder seems to me no more than the fit climax to a creative work that has been ineffably beautiful and marvellous in all its myriad stages." Fiske gives some further definition of social evolution in man, in his "Cosmic Philosophy" (1874). He there denies the incompatibility of free-will with causation, saying that "it is the doctrine of lawlessness, and not the causationist doctrine, which is incompatible with liberty and destructive of responsibility."[54] He further postulates heterogeneity of the environment as "the chief proximate determining cause of social progress," and defines such evolution as "a continuous establishment of psychical relations within the community, in conformity to physical and psychical relations arising in the environment, during which both the community and the environment pass from a state of relatively indefinite, incoherent homogeneity to a state of relatively definite, coherent heterogeneity; and during which the constituent units of the community become ever more distinctly individual."[55] "The progress of a community, as of an organism, is a process of _adaptation_--the continuous establishment of inner relations in conformity to outer relations. If we contemplate material civilization under its widest aspect, we discover its legitimate aim to be the attainment and maintenance of an equilibrium between the wants of men and the outward means of satisfying them. And while approaching this goal, society is ever acquiring in its economic structure both greater heterogeneity and greater specialization. It is not only that agriculture, manufactures, commerce, legislation, the acts of the ruler, the judge, and the physician, have, since ancient times, grown immeasurably multiform, both in their processes and in their appliances; but it is also that this specialization has resulted in the greatly increased ability of society to adapt itself to the emergencies by which it is now beset."[56] Religion, too, is adjustment; form after form has been outgrown and perished, yet the life of Christianity, incorporated in ever higher forms, is continually renewed. The omission of the moral feeling, as a factor, from Comte's interpretation of the progress of society, is a fatal defect, since moral and social progress depend more on feelings than on ideas. As Wallace shows, tribes which combined for mutual help and protection, restrained appetite by foresight, and felt sympathy, would have an advantage in the struggle for existence.