But a spoken language in its development is progressive as well as conservative. To certain modifying influences it is especially sensitive. It is fond of the concrete, picturesque, and novel, and has a high appreciation of humor. These tendencies lead it to invent many new words and expressions which must wait months, years, perhaps a generation, before they are accepted in literature. Sometimes they are never accepted. The history of such words as buncombe, dude, Mugwump, gerrymander, and joy-ride illustrate for English the fact that words of a certain kind meet a more hospitable reception in the spoken language than they do in literature. The writer of comedy or farce, the humorist, and the man in the street do not feel the constraint which the canons of good usage put on the serious writer. They coin new words or use old words in a new way or use new constructions without much hesitation. The extraordinary material progress of the modern world during the last century has undoubtedly stimulated this tendency in a remarkable way, but it would seem as if the Latin of the common people from the time of Plautus to that of Cicero must have been subjected to still more innovating influences than modern conversational English has. During this period the newly conquered territories in Spain, northern Africa, Greece, and Asia poured their slaves and traders into Italy, and added a great many words to the vocabulary of every-day life. The large admixture of Greek words and idioms in the language of Petronius in the first century of our era furnishes proof of this fact. A still greater influence must have been felt within the language itself by the stimulus to the imagination which the coming of these foreigners brought, with their new ideas, and their new ways of looking at things, their strange costumes, manners, and religions.