It becomes necessary to investigate the Greek conceptions of nature and her law. The word [Greek: physis], which was rendered in the Latin _natura_ and our _nature_, denoted beyond all doubt originally the material universe, but it was the material universe contemplated under an aspect which--such is our intellectual distance from those times--it is not very easy to delineate in modern language. Nature signified the physical world regarded as the result of some primordial element or law. The oldest Greek philosophers had been accustomed to explain the fabric of creation as the manifestation of some single principle which they variously asserted to be movement, force, fire, moisture, or generation. In its simplest and most ancient sense, Nature is precisely the physical universe looked upon in this way as the manifestation of a principle. Afterwards, the later Greek sects, returning to a path from which the greatest intellects of Greece had meanwhile strayed, added the _moral_ to the _physical_ world in the conception of Nature. They extended the term till it embraced not merely the visible creation, but the thoughts, observances, and aspirations of mankind. Still, as before, it was not solely the moral phenomena of human society which they understood by _Nature_, but these phenomena considered as resolvable into some general and simple laws. Now, just as the oldest Greek theorists supposed that the sports of chance had changed the material universe from its simple primitive form into its present heterogeneous condition, so their intellectual descendants imagined that but for untoward accident the human race would have conformed itself to simpler rules of conduct and a less tempestuous life. To live according to _nature_ came to be considered as the end for which man was created, and which the best men were bound to compass. To live according to _nature_ was to rise above the disorderly habits and gross indulgences of the vulgar to higher laws of action which nothing but self-denial and self-command would enable the aspirant to observe. It is notorious that this proposition--live according to nature--was the sum of the tenets of the famous Stoic philosophy. Now on the subjugation of Greece that philosophy made instantaneous progress in Roman society. It possessed natural fascinations for the powerful class who, in theory at least, adhered to the simple habits of the ancient Italian race, and disdained to surrender themselves to the innovations of foreign fashions. Such persons began immediately to affect the Stoic precepts of life according to nature--an affectation all the more grateful, and, I may add, all the more noble, from its contrast with the unbounded profligacy which was being diffused through the imperial city by the pillage of the world and by the example of its most luxurious races. In the front of the disciples of the new Greek school, we might be sure, even if we did not know it historically, that the Roman lawyers figured.