It is probably true to say that no other primitive Christian writing has had so marked an effect on all later attempts to systematize the Christian creed.
We may define these courses by the terms esoteric and exoteric - the former the philosophy of the school, cultivated principally at the universities, trying to systematize everything and reduce all our knowledge to an intelligible principle, losing in this attempt the deeper meaning of Leibnitz's philosophy; the latter the unsystematized philosophy of general culture which we find in the work of the great writers of the classical period, Lessing, Winkelmann, Goethe, Schiller and Herder, all of whom expressed in some degree their indebtedness to Leibnitz.
Writings of Spencer embody the spirit of Descartes in the knowledge of our own day, and may be regarded as the Principes de la philosophic of the 19th century; while, whatever hesitation may not unfrequently be felt by less daring minds in following Haeckel in many of his speculations, his attempt to systematize the doctrine of evolution and to exhibit its influence as the central thought of modern biology, cannot fail to have a far-reaching influence on the progress of science.
An exact and conscientious worker, he did much to improve and systematize the processes of analytical chemistry and mineralogy, and his appreciation of the value of quantitative methods led him to become one of the earliest adherents of the Lavoisierian doctrines outside France.
He thus admits that to philosophize is to systematize, but holds that every systematization is narrowly circumscribed, and is therefore to be solved and completed with ever new systematization.