Institutions Oratoires, 1, 1, 32 sq[1]:

XXXII. incredibile est quantum morae lectioni festinatione adiciatur. Hinc enim accidit dubitatio intermissio repetitio plus quam possunt audentibus, deinde cum errarunt etiam iis quae iam sciunt diffidentibus. XXXIII. Certa sit ergo in primis lectio, deinde coniuncta, et diu lentior, donec exercitatione contingat emendata velocitas. XXXIV. Nam prospicere in dextrum, quod omnes praecipiunt, et providere non rationis modo sed usus quoque est, quoniam sequentia intuenti priora dicenda sunt, et, quod difficillimum est, dividenda intentio animi, ut aliud voce aliud oculis agatur. Illud non paenitebit curasse, cum scribere nomina puer, quemadmodum moris est, coeperit, ne hanc operam in vocabulis vulgaribus et forte occurrentibus perdat. XXXV. Protinus enim potest interpretationem linguae secretioris, id est quas Graeci glossas vocant, dum aliud agitur ediscere, et inter prima elementa consequi rem postea proprium tempus desideraturam. Et quoniam circa res adhuc tenues moramur, ii quoque versus qui ad imitationem scribendi proponentur non otiosas velim sententias habeant, sed honestum aliquid monentis. XXXVI. Prosequitur haec memoria in senectutem et inpressa animo rudi usque ad mores proficiet.

Trad. H. E. Butler[2]

32 You will hardly believe how much reading is delayed by undue haste. If the child attempts more than his powers allow, the inevitable result is hesitation, interruption and repetition, and the mistakes which he makes merely lead him to lose confidence in what he already knows. 33 Reading must therefore first be sure, then connected, while it must be kept slow for a considerable time, until practice brings speed unaccompanied by error. 34 For to look to the right, which is regularly taught, and to look ahead depends not so much on precept as on practice; since it is necessary to keep the eyes on what follows while reading out what precedes, with the resulting difficulty that the attention of the mind must be divided, the eyes and voice being differently engaged. It will be found worth while, when the boy begins to write out words in accordance with the usual practice, to see that he does not waste his labour in writing out common words of everyday occurrence. 35 He can readily learn the explanations or glosses, as the Greeks call them, of the more obscure words by the way and, while he is still engaged on first rudiments, acquire what would otherwise demand special time to be devoted to it. And as we are still discussing minor details, I would urge that the lines, which he is set to copy, should not express thoughts of no significance, but convey some sound moral lesson. 36 He will remember such aphorisms even when he is an old man, and the impression made upon his unformed mind will contribute to the formation of his character.