I mean, if we are quoting Gygax ...
"As this book is the exclusive precinct of the DM, you must view any non-DM player possessing it as something less than worthy of honorable death. Peeping players there will undoubtedly be, but they are simply lessening their own enjoyment of the game by taking away some of the sense of wonder that otherwise arises from a game which has rules hidden from participants. It is in your interests, and in theirs, to discourage possession of this book by players. If any of your participants do read herein, it is suggested that you assess them a heavy fee for consulting 'sages' and other sources of information not normally attainable by the inhabitants of your milieu. If they express knowledge which could only be garnered by consulting these pages, a magic item or two can be taken as payment - insufficient, but perhaps it will tend to discourage such actions."
DMG p. 8 (forward)
"Know the game systems, and you will know how and when to take upon yourself the ultimate power. To become the final arbiter, rather than the interpreter of the rules, can be a difficult and demanding task, and it cannot be undertaken lightly, for your players expect to play this game, not one made up on the spot. By the same token, they are playing the game the way you, their DM, imagines and creates it. Remembering that the game is greater than its parts, and knowing all of the parts, you will have overcome the greater part of the challenge of being a referee. Being a true DM requires cleverness and imagination which no set of rules books can bestow. Seeing that you were clever enough to buy this volume, and you have enough imagination to desire to become the maker of a fantasy world, you are almost there already! Read and become familiar with the contents of this work and the one written for players, learn your monsters, and spice things up with some pantheons of super-powerful beings. Then put your judging and refereeing ability into the creation of your own personal milieu, and you have donned the mantle of Dungeon Master. Welcome to the exalted ranks of the overworked and harrassed, whose cleverness and imagination are all too often unappreciated by cloddish characters whose only thought in life is to loot, pillage, slay, and who fail to appreciate the hours of preparation which went into the creation of what they aim to destroy as cheaply and quickly as possible. As a DM you must live by the immortal words of the sage who said: 'Never give a sucker an even break.' Also, don‘t be a sucker for your players, for you‘d better be sure they follow sage advice too. As the DM, you have to prove in every game that you are still the best. This book is dedicated to helping to assure that you are."
DMG p. 9 (Introduction)
"In many situations it is correct and fun to have the players dice such things as melee hits or saving throws. However, it is your right to control the dice at any time and to roll dice for the players. You might wish to do this to keep them from knowing some specific fact. You also might wish to give them an edge in finding a particular clue, e.g. a secret door that leads to a complex of monsters and treasures that will be especially entertaining. You do have every right to overrule the dice at any time if there is a particular course of events that you would like to have occur."
DMG p. 110 (conducting the game)
"Strong steps short of expulsion can be an extra random monster die, obviously rolled, the attack of an ethereal mummy (which always strikes by surprise, naturally), points of damage from "blue bolts from the heavens" striking the offender's head, or the permanent loss of a point of charisma (appropriately) from the character belonging to the offender. If these have to be enacted regularly, then they are not effective and stronger measures must be taken. Again, the ultimate answer to such a problem is simply to exclude the disruptive person from further gatherings."
DMG p. 110 (handling troublesome players)
