On Knowledge, Ignorance, and Pride

From Jean-Jacques Rousseau's Emile:

Human intelligence has its limits, and not only can a man not know everything, but he cannot even know in its entirety the little that other men know. Since the contrary of every false proposition is a truth, the number of truths is as unfathomable as the number of errors. We must, therefore, choose what to teach as well as when to teach it. Of the knowledge within our reach some is false, some is useless, some merely serves to feed the pride of him who has it....

Beware of the specious attraction of falsehood and the intoxicating fumes of pride. Remember, remember always, that ignorance never did any harm, that error alone is fatal, and that we do not lose our way because of what we do not know but because of what we think we know.