how does Beatty cleverly punish montag at work

Montag has reached the point where his heart is no longer in his work. He's become fed up with destroying books and burning the properties of those found reading them. So one day he calls in sick. Beatty pays Montag a visit at his home and tells him, among other things, that it's common for firemen to have doubts about their work. But he also warns him that if any fireman should steal a book for themselves, they must return it in 24 hours, or they'll be arrested, and their property and all their belongings will be burned.
To drive home the point, Beatty embarrasses Montag when he returns to work. He tells him about a dream he had the previous night where the two men were throwing quotations from books at each other to justify their respective positions. Beatty takes great delight in informing Montag that he used arguments from books to refute Montag's defense of them. Beatty has clearly sensed Montag's growing hostility toward his work, and is keen to remind him of the overriding importance of doing his duty as a fireman. By quoting directly from books, he's hoping to appeal to reason, as well as referencing the none-too-subtle threats he made earlier when he visited Montag's home.