I applaud your devotion to philosophy; I rejoice to hear that your soul has set sail, like the returning Ulysses, for its native land—that glorious, that only real country—the world of unseen truth. To follow philosophy, the senator Rogatianus, one of the noblest of my disciples, gave up the other day all but the whole of his patrimony, set free his slaves, and surrendered all the honours of his station. Tidings have reached us that Valerian has been defeated, and is now in the hands of Sapor. The threats of Franks and Allemanni, of Goths and Persians, are alike terrible by turns to our degenerate Rome. In days like these, crowded with incessant calamities, the inducements to a life of contemplation are more than ever strong. Even my quiet existence seems now to grow somewhat sensible of the advance of years. Age alone I am unable to debar from my retirement. I am weary already of this prison-house, the body, and calmly await the day when the divine nature within me shall be set free from matter. The Egyptian priests used to tell me that a single touch with the wing of their holy bird could charm the crocodile into torpor; it is not thus speedily, my dear friend, that the pinions of your soul will have power to still the untamed body. The creature will yield only to watchful, strenuous constancy of habit. Purify your soul from all undue hope and fear about earthly things, mortify the body, deny self,—affections as well as appetites, and the inner eye will begin to exercise its clear and solemn vision. You ask me to tell you how we know, and what is our criterion of certainty. To write is always irksome to me. But for the continual solicitations of Porphyry, I should not have left a line to survive me. For your own sake and for your father’s, my reluctance shall be overcome.