To come now to a point of much less, but yet of very great consequence at your first setting out. Be extremely upon your guard against vanity, the common failing of inexperienced youth; but particularly against that kind of vanity that dubs a man a coxcomb; a character which, once acquired, is more indelible than that of the priesthood. It is not to be imagined by how many different ways vanity defeats its own purposes. One man decides peremptorily upon every subject, betrays his ignorance upon many, and shows a disgusting presumption upon the rest. Another desires to appear successful among the women; he hints at the encouragement he has received, from those of the most distinguished rank and beauty, and intimates a particular connection with some one; if it is true, it is ungenerous; if false, it is infamous: but in either case he destroys the reputation he wants to get. Some flatter their vanity by little extraneous objects, which have not the least relation to themselves; such as being descended from, related to, or acquainted with, people of distinguished merit and eminent characters. They talk perpetually of their grandfather such-a-one, their uncle such-a-one, and their intimate friend Mr. Such-a-one, with whom, possibly, they are hardly acquainted. But admitting it all to be as they would have it, what then? Have they the more merit for those accidents? Certainly not. On the contrary, their taking up adventitious, proves their want of intrinsic merit; a rich man never borrows. Take this rule for granted, as a never-failing one: That you must never seem to affect the character in which you have a mind to shine. Modesty is the only sure bait when you angle for praise. The affectation of courage will make even a brave man pass only for a bully; as the affectation of wit will make a man of parts pass for a coxcomb. By this modesty I do not mean timidity and awkward bashfulness. On the contrary, be inwardly firm and steady, know your own value whatever it may be, and act upon that principle; but take great care to let nobody discover that you do know your own value. Whatever real merit you have, other people will discover, and people always magnify their own discoveries, as they lessen those of others.
For God’s sake, revolve all these things seriously in your thoughts, before you launch out alone into the ocean of Paris. Recollect the observations that you have yourself made upon mankind, compare and connect them with my instructions, and then act systematically and consequentially from them; not ‘au jour la journee’. Lay your little plan now, which you will hereafter extend and improve by your own observations, and by the advice of those who can never mean to mislead you; I mean Mr. Harte and myself.
London, May 24., O. S. 1750