passed through is absolutely _conquered_, and that you are leaving no unsolved difficulties _behind_ you, which will be sure to turn up again later on, your triumphal progress will be easy and delightful. Otherwise, you will find your state of puzzlement get worse and worse as you proceed, till you give up the whole thing in utter disgust. (3) When you come to any passage you don't understand, _read it again_: if you _still_ don't understand it, _read it again_: if you fail, even after _three_ readings, very likely your brain is getting a little tired. In that case, put the book away, and take to other occupations, and next day, when you come to it fresh, you will very likely find that it is _quite_ easy. (4) If possible, find some genial friend, who will read the book along with you, and will talk over the difficulties with you. _Talking_ is a wonderful smoother-over of difficulties. When _I_ come upon anything----in Logic or in any other hard subject----that entirely puzzles me, I find it a capital plan to talk it over, _aloud_, even when I am all alone. One can explain things so _clearly_ to one's self! And then, you know, one is so _patient_ with one's self: one _never_ gets irritated at one's own stupidity! If, dear Reader, you will faithfully observe these Rules, and so give my little book a really _fair_ trial, I promise you, most confidently, that you will find Symbolic Logic to be one of the most, if not _the_ most, fascinating of mental recreations! In this First Part, I have carefully avoided all difficulties which seemed to me to be beyond the grasp of an intelligent child of (say) twelve or fourteen years of age. I have myself taught most of its contents, _vivâ voce_, to _many_ children, and have found them take a real intelligent interest in the subject. For those, who succeed in mastering Part I, and who begin, like Oliver, "asking for more," I hope to provide, in Part II, some _tolerably_ hard nuts to crack----nuts that will require all the nut-crackers they happen to possess! pg-xiii Mental recreation is a thing that we all of us need for our mental health; and you may get much healthy enjoyment, no doubt, from Games, such as Back-gammon, Chess, and the new Game "Halma". But, after all, when you have made yourself a first-rate player at any one of these Games, you have nothing real to _show_ for it, as a _result!_ You enjoyed the Game, and the victory, no doubt, _at the time_: but you have no _result_ that you can treasure up and get real _good_ out of. And, all the while, you have been leaving unexplored a perfect _mine_ of wealth. Once master the machinery of Symbolic Logic, and you have a mental occupation always at hand, of absorbing interest, and one that will be of real _use_ to you in _any_ subject you may take up. It will give you clearness of thought----the ability to _see your way_ through a