Ab urbe condita

Titus Livius (Livy)

Livy. History of Rome, Volumes 1-2. Roberts, Canon, Rev, translator. London, New York: J. M. Dent and Sons; E. P. Dutton and Co., 1912.

Any one who considers these factors either separately or in combination will easily see that as the Roman empire proved invincible against other kings and nations, so it would have proved invincible against Alexander.

Let us, first of all, compare the commanders on each side. I do not dispute that Alexander was an exceptional general, but his reputation is enhanced by the fact that he died while still young and before he had time to experience any change of fortune.