--- Francis Bacon, "Of Studies"
Excerpt
And therefore, if a man write little, he had need have a great memory; if he confer little, he had need have a present wit: and if he read little, he had need have much cunning, to seem to know that he doth not. Histories make men wise; poets witty; the mathematics subtile; natural philosophy deep; moral grave; logic and rhetoric able to contend.
For discussion, see enotes, 'What does Francis Bacon mean by "writing makes an exact man" in his essay "Of Studies"?' This Samuel Johnson quote cited there by William Delaney resonated with me:
Composition is, for the most part, an effort of slow diligence and steady perseverance, to which the mind is dragged by necessity or resolution, and from which the attention is every moment starting to more delightful amusements.