Yet for a long time mortal men have discussed the question whether success in arms depends more on strength of body or excellence of mind; for before you begin, deliberation is necessary, when you have deliberated, prompt action. Thus each of these, being incomplete of itself, requires the other’s aid.

[Sed diu magnum inter mortalis certamen fuit vine corporis an virtute animi res militaris magis procederet. Nam et prius quam incipias, consulto, et ubi consulueris, mature facto opus est. Ita utrumque per se indigens alterum alterius auxilio eget.]

Sallust (c. 86-35 BC) Roman historian and politician [Gaius Sallustius Crispus]
Bellum Catilinae [The War of Catiline; The Conspiracy of Catiline], ch. 1, sent. 5-7 [tr. Rolfe (1931)]
    (Source)

Original Latin. Alt. trans.:

"But a just estimate of our mental and bodily faculties was not easily made. Which of them was most conducive to the success of military operations, was in former times a question much agitated, and long undecided. It is evident, however, that before the undertaking of a warlike enterprise, judgment is required to concert and plan the necessary measures; vigor in execution is equally necessary. The powers of man, in their separate functions feeble and ineffectual, demand each other's aid, and flourish by mutual assistance." [tr. Murphy (1807)]

"It has, however, been a great and long debate, whether success in war is most owing to bodily strength or mental abilities: for, as counsel is necessary before we enter on action, after measures are duly concerted, speedy execution is equally necessary; so that neither of these being sufficient singly, they prevail only by the assistance of each other." [tr. Rose (1831)]

"But there has been for a long time a great debate amongst mortals, whether the science of war advanced more by the strength of body or by the abilities of the mind. For both before you begin there is need of counsel; and when you have counselled, there is need of vigorous execution. So whilst both by themselves are defective, the one is strengthened by the assistance of the other." [Source (1841)]

"Yet it was long a subject of dispute among mankind, whether military efforts were more advanced by strength of body, or by force of intellect. For, in affairs of war, it is necessary to plan before beginning to act, and, after planning, to act with promptitude and vigor. Thus, each being insufficient of itself, the one requires the assistance of the other." [tr. Watson (1867)]

"Not it was long hotly contested among men whether military success was more advanced by mental ability or by bodily strength, for what we need is deliberation before we begin, and after deliberation, then well-timed action; either of itself is deficient and lacks the other's help." [tr. Pollard (1882)]

"Yet for a long time there was considerable dispute amongst mortals as to whether it was through the power of the body or the prowess of the mind that military affairs made greater progress. For, before you begin, deliberation is necessary, and, when you have deliberated, speedy action: hence each element, deficient on its own, requires the help of the other." [tr. Woodman (2007)]