We have seen what was the guiding principle of Cicero’s philosophical method. By interrogating all the systems of his time, he hoped to elicit their points of agreement, and to utilise the result for the practical purposes of life. As actually applied, the effect of this method was not to reconcile the current theories with one another, nor yet to lay the foundation of a more comprehensive philosophy, but to throw back thought on an order of ideas which, from their great popularity, had been incorporated with every system in turn, and, for that very reason, seemed to embody the precise points on which all were agreed. These were the idea of Nature, the idea of mind or reason, and the idea of utility. We have frequently come across them in the course of the present work. Here it will suffice to recall the fact that they had been first raised to distinct consciousness when the results of early Greek thought were brought into contact with the experiences of Greek life, and more especially of Athenian life, in the age of Pericles. As originally understood, they gave rise to many complications and cross divisions, arising from what was considered to be their mutual incompatibility or equivalence. Thus Nature was openly rejected by the sceptical Sophists, ignored by Socrates, and, during a long period of his career, treated with very little respect by Plato; reason, in its more elaborate forms, was slighted by the Cynics, and employed for its own destruction by the Megarians, in both cases as an enemy to utility; while to Aristotle the pure exercise of reason was the highest utility of any, and Nature only a lower manifestation of the same idealising process. At a later period, we find Nature accepted as a watchword by Stoics, Epicureans, and Sceptics alike, although, of course, each attached a widely different meaning to the term; the supremacy of reason, without whose aid, indeed, their controversies could not have been carried on, is recognised with similar unanimity; and each sect lays exclusive stress on the connexion of its principles with human happiness, thus making utility the foremost consideration in philosophy. Consequently, to whatever system a Roman turned, he would recognise the three great regulative conceptions of Greek thought, although frequently enveloped in a network of fine-spun distinctions and inferences which to him must have seemed neither natural nor reasonable nor useful. On the other hand, apart from such subtleties, he could readily translate all three into terms which seemed to show that, so far from being divided by any essential incompatibility, they did but represent different aspects of a single harmonious ideal. Nature meant simplicity, orderliness, universality, and the spontaneous consentience of unsophisticated minds. Reason meant human dignity, especially as manifested in the conquest of fear and of desire. And whatever was natural and reasonable seemed to satisfy the requirements of utility as well.