I’ve found myself referencing this passage of J.S. Mill’s in On Liberty quite often recently, so I thought I’d save it here.
All languages and literatures are full of general observations on life, both as to what it is, and how to conduct oneself in it; observations which everybody knows, which everybody repeats, or hears with acquiescence, which are received as truisms, yet of which most people first truly learn the meaning, when experience, generally of a painful kind, has made it a reality to them. How often, when smarting under some unforeseen misfortune or disappointment, does a person call to mind some proverb or common saying, familiar to him all his life, the meaning of which, if he had ever before felt it as he does now, would have saved him from the calamity. There are indeed reasons for this, other than the absence of discussion: there are many truths of which the full meaning cannot be realized, until personal experience has brought it home.
Though we may dismiss common expressions as clichés, they do contain some wisdom. That said, we shouldn’t be too hard on ourselves for only truly learning that lesson once having lived it; words alone are hard to internalize.
But, as Mill goes on, we might better learn these things if we listen to (and, perhaps, engage in conversation with) those who have lived those lessons:
But much more of the meaning even of these would have been understood, and what was understood would have been far more deeply impressed on the mind, if the man had been accustomed to hear it argued pro and con. by people who did understand it. The fatal tendency of mankind to leave off thinking about a thing when it is no longer doubtful, is the cause of half their errors.