It has been some time since Quintilian graced this page. But he has some good reminders for those of us returning to the classroom.
Quintilian, Institutio Oratorio 10.1
“But these rules of rhetoric, even though they are critical to understanding, are not on their own enough to instill power of speech unless that certain quality is also strong, the one the Greeks call ἕξις [“self-possession”?]. I know that many have deliberated whether this is best developed by writing, reading or speaking—and it is a question meriting very serious consideration, if we could ever be content with only one of the three. But, truly, they are so interconnected and dependent on each other that if one is lacking, then the others are pursued in vain. For eloquence will never be forceful or flourishing unless it acquires strength from practice by writing; such practice bereft of the lessons of reading wanders like a ship without captain; and whoever knows what should be said and how to say it—if he does not also have eloquence practiced for combat and every outcome—will recline on a locked-up treasure.”
Sed haec eloquendi praecepta, sicut cogitationi sunt necessaria, ita non satis ad vim dicendi valent nisi illis firma quaedam facilitas, quae apud Graecos hexis nominatur, accesserit: ad quam scribendo plus an legendo an dicendo conferatur, solere quaeri scio. Quod esset diligentius nobis examinandum [citra] si qualibet earum rerum possemus una esse contenti; II. verum ita sunt inter se conexa et indiscreta omnia ut, si quid ex his defuerit, frustra sit in ceteris laboratum. Nam neque solida atque robusta fuerit umquam eloquentia nisi multo stilo vires acceperit, et citra lectionis exemplum labor ille carens rectore fluitabit, et qui sciet quae quoque sint modo dicenda, nisi tamen in procinctu paratamque ad omnis casus habuerit eloquentiam, velut clausis thesauris incubabit.
Full Latin text.