The subject, of inquiry last week was Facts and Principies, and the best method of acquiring them. We recommcnded to Isaiah to get a standard work on that subject on which he wished for information. Wesaid to him, Buy it pay for it, write your name in it, and have it in every sense, your own. Next we proposed reading carefully in the work art Jiour a 'ftay tiÃ¼ you getthrough it. And remember and begin at the beginning, reading preface and introduction. Then conimencc anew, marking with your pencil every important fact or principie that strikes your attention, so that you will notice it whenever you sec the page again. So if you find any positions you deern false or doubtful, note the fact in the margin. Should you find important statements to which you desire hereaftcr to refer, make an index of the pages where they may be found in the blank leaves of your book. Do not be afraid of spoiling it by these marks, you bought it, not to see, but to bc used in the manner that will best inform your mind. To fix the truth you read still more in your memory, adopt the following method, which has been practiced with great advantages. Beforc conimencingyoursecond reading, m:ke yourself a little book, of threo or four sheets of foolscap, folded small, and stitched. In this book, as you read, enter on the different pages the subjects of the different chapters. For instanco, if the subject bo Political Economy, your pages will bo headed, Wealth, Capital, Money, Industry, Natural Agents, DivisiÃ³n of Labor. Poor Laws, Interest, Exchange, Banks, Wages, Rent, Public Consumption, Taxation, &c. Under each of these heads, write in as few words as possible, those principies or tacts which secm to you most important to be remembered, numbering cach paragraph 1, 2, 3, &c. as you proceed, you will do well also to add such remarks and queries of your own as occur to you. Should you wish to follow up your studies on the same subject, get anotlier standard work respecting it, and go through with it in the saine way, minuting under the appropriate heads in your little book, all the new ideas you derive from the perusal of that volume.Theadvantagos ofsuch a thorough and systematic study of a single subject are numerous and great. When you gct through with your book, you will have trnnscribed every important fact or principie laid down in the work, and have n complete epitome of the science written out by yourself, you will also have an enlarged and comprehensivo view of the wholo subject transcribed into your vund - an advantage, the extent of which you will never appreciate till you attain it, you will get a greater influence in society, you will not be depended on Squire A., orLawyer B., or Judge C. for youropinions, but can go at once to the productionsof the mostgifted writers and thingers of every age. This will give you confidenco on a subject which you know that you understand. You can, accomplish more by having a thorough knowledgo of your subject. A person of only limited general information, but ihoroughly conversant with a particular subject, can not only meet but often overthrow an opponent not wcll inibrmcd on that matterhough far his superior in general knowl3tlge. These facts and principies, once horoughly fixed in your mind, will bejome the guidesof your life ; and onevery jccasion where tliey are called in question yoi will not fail to revert to them with jonfidence. Thus, should the propriety f establishing a rate of interest hy law :orne up for discussion in your debuting school, instead of being dependand on tho liearsay of others, you can adduce those large and expanded views -which havo been most conclusivo with the profoundest writersand thinkers. Add to these your own reilections, and you will have the very best matcrials for forming a correct opiniÃ³n, overthrowing your opponents, and acquiring a high reputation for yoursclf. What do you say : Ã¼ will tace a long time ? Not so long as you think for. Stcady, systematic perseveing industry will accomplish wonders.- Supposo Dr. Wayland was your next neighbor, and he should ofler to convey to you in 100 hours all the information he had been able to acquire on Political Ecoiiomy by the labor of twenty years : VVould you consider a hundred hours a very long time ; You would not. AU that knowledge you can have, by devoting only an hour a day for a hundred days to his work on the subject. Hia work will then be yours : and its positiora and argumenta, for all practical purposes, will bo as valuable to you as to him. - Isaiah ! you can't excel by skimming lightly over the surface ! Be thorough.