Laudator Temporis Acti

Vegetius, Epitome of Military Science 1.16.1-3 (tr. N.P. Milner):

It is advisable that recruits be thoroughly trained at casting stones by hand or with slings. The inhabitants of the Balearic Isles are said to have been first to discover the use of slings and to have practised with such expertise that mothers did not allow their small sons to touch any food unless they had hit it with a stone shot from a sling. Often, against soldiers armed with helmets, cataphracts and cuirasses, smooth stones shot with a sling or "sling-staff" are more dangerous than any arrows, since while leaving the limbs intact they inflict a wound that is still lethal, and the enemy dies from the blow of the stone without loss of blood. That slingers served in all battles of the ancients is known to everyone. This weapon should be learned by all recruits with frequent exercise, because it is no effort to carry a sling.

ad lapides vero vel manibus vel fundis iaciendos exerceri diligenter convenit iuniores. fundarum usum primi Balearium insularum habitatores et invenisse et ita perite exercuisse dicuntur ut matres parvos filios nullum cibum contingere sinerent nisi quem ex funda destinato lapide percussissent. saepe enim adversum bellatores cassidibus catafractis loricisque munitos teretes lapides de funda vel fustibalo destinati sagittis sunt omnibus graviores, cum membris integris letale tamen vulnus importent et sine invidia sanguinis hostis lapidis ictu intereat. in omnibus autem veterum proeliis funditores militasse nullus ignorat. quae res ideo ab universis tironibus frequenti exercitio discenda est quia fundam portare nullus est labor.

loricis del. Gemoll

Florus, Epitome of Roman History 1.43.5 (on the Balearic War; tr. Edward Seymour Forster):

They fight with three slings apiece; and who can wonder that their aim is so accurate, seeing that this is their only kind of arm and its employment their sole pursuit from infancy? A boy receives no food from his mother except what he has struck down under her instruction.

tribus quisque fundis proeliantur. certos esse quis miretur ictus, cum haec solo genti arma sint, id unum ab infantia studium? cibum puer a matre non accipit, nisi quem ipsa monstrante percusserit.