Edward Campbell has kindly translated for us this letter of Isidore of Pelusium, from the Patrologia Graeca text. It came to my attention after a correspondent asked whether it referred to the Three Hundred Spartans.
To Esaias[1] the soldier.
To[2] the disorderly soldier.
If, from among your weapons, you consider your spears and your helmet and your breast-plate to be an assurance for your well-being, while you plunder and desolate the highways, know that many who had armed themselves more impregnably than you won for themselves[3] a most lamentable death. Among us[4] are recorded, on the one hand, Oreb, Zebah, Zalmunna, Abimelech and Goliath, and Absalom,[5] and as many others who were like them. Among those outside,[6] on the other hand, are the Hectors, the Ajaxes, and the Lacedaimonians[7] themselves who, above all others, were prideful of their strength, since they did not possess justice in proportion[8] to their power. If, then, you do not wish to be a worthless soldier, arrange yourself at once toward the spiritual war and wage war rather upon your own disorderliness.
[1] A more normal English rendering would give “Isaiah.”
[2] Possibly, “Against the disorderly soldier.”
[3] Or simply, “obtained.”
[4] i.e. Characters from the Old and New Testaments.
[5] See Judges 7, 8, and 9; 1 Samuel 17; 2 Samuel 13.
[6] i.e. Characters from Greek literature.
[7] i.e. the Spartans.
[8] Lit, “running along with their power,” a slightly confusing phrase. Isidore seems to mean that the Spartans’ power far surpassed their justice, hence they only had their power to be proud of.