Date: April 26, 1695; 1708

"Meditating by one's self is like digging in the Mine; it often, perhaps, brings up maiden Earth, which never came near the Light before; but whether it contain any Metal in it, is never so well tried as in Conversation with a knowing judicious Friend, who carries about him the true Touch-stone, ...

— Locke, John (1632-1704)

Date: 1709, 1714

"We polish one another, and rub off our Corners and rough Sides by a sort of amicable Collision. To restrain this, is inevitably to bring a Rust upon Mens Understandings."

— Cooper, Anthony Ashley, third earl of Shaftesbury (1671-1713)

Date: January 28, 1753

"I have heard that his understanding was rather hurt by the absolute retirement in which he lived, and indeed he had an imagination too lively to be trusted to itself; the treasures of it were inexhaustible, but for want of commerce with mankind he made that rich oar into bright but useless medal...

— Montagu [née Robinson], Elizabeth (1718-1800)