DEAR BOY: There are two sorts of understandings; one of which hinders a man from ever being considerable, and the other commonly makes him ridiculous; I mean the lazy mind, and the trifling, frivolous mind: Yours, I hope, is neither. The lazy mind will not take the trouble of going to the bottom of anything; but, discouraged by the first difficulties (and everything worth knowing or having is attained with some), stops short, contents, itself with easy, and consequently superficial knowledge, and prefers a great degree of ignorance to a small degree of trouble. These people either think, or represent most things as impossible; whereas, few things are so to industry and activity. But difficulties seem to them, impossibilities, or at least they pretend to think them so--by way of excuse for their laziness. An hour's attention to the same subject is too laborious for them; they take everything in the light in which it first presents itself; never consider, it in all its different views; and, in short, never think it through. The consequence of this is that when they come to speak upon these subjects, before people who have considered them with attention; they only discover their own ignorance and laziness, and lay themselves open to answers that put them in confusion. Do not then be discouraged by the first difficulties, but 'contra audentior ito'; and resolve to go to the bottom of all those things which every gentleman ought to know well. Those arts or sciences which are peculiar to certain professions, need not be deeply known by those who are not intended for those professions. As, for instance; fortification and navigation; of both which, a superficial and general knowledge, such as the common course of conversation, with a very little inquiry on your part, will give you, is sufficient. Though, by the way, a little more knowledge of fortification may be of some use to you; as the events of war, in sieges, make many of the terms, of that science occur frequently in common conversation; and one would be sorry to say, like the Marquis de Mascarille in Moliere's 'Precieuses Ridicules', when he hears of 'une demie lune, Ma foi! c'etoit bien une lune toute entiere'. But those things which every gentleman, independently of profession, should know, he ought to know well, and dive into all the depth of them. Such are languages, history, and geography ancient and modern, philosophy, rational logic; rhetoric; and, for you particularly, the constitutions and the civil and military state of every country in Europe: This, I confess; is a pretty large circle of knowledge, attended with some difficulties, and requiring some trouble; which, however; an active and industrious mind will overcome; and be amply repaid. The trifling and frivolous mind is always busied, but to little purpose; it takes little objects for great ones, and throws away upon trifles that time and attention which only important things deserve. Knick-knacks;