John Locke tells a “gentleman” how important reading and thinking is to a man of his station whose “proper calling” should be the service of his country (late 1600s)

Found in The Works, vol. 2 An Essay concerning Human Understanding Part 2 and Other Writings
John Locke begins his advice to a Gentleman on the importance of reading with the following thoughts:
Reading is for the improvement of the understanding.
The improvement of the understanding is for two ends; first, for our own increase of knowledge; secondly, to enable us to deliver and make out that knowledge to others.
The latter of these, if it be not the chief end of study in a gentleman; yet it is at least equal to the other, since the greatest part of his business and usefulness in the world is by the influence of what he says, or writes to others.
Just as Vicesimus Knox tried to persuade a young nobleman under his care to abandon the aristocratic notion that he had a right to rule over others, John Locke tells his “gentleman” friend that if he wished to be of true service to his country it might be more profitable to read good books than to pursue other more “gentlemanly” activities.