When you wander, as you often delight to do, you wander indeed, and give never such satisfaction as the curious time requires. This is not caused by any natural defect, but first for want of election, when you, having a large and fruitful mind, should not so much labour what to speak as to find what to leave unspoken. Rich soils are often to be weeded.
Letter of Expostulation to Coke, reported in Bartlett's Familiar Quotations, 10th ed. (1919).