The tendency of Renaissance humanists to define Cicero (106^43 B.C.) as the sole model for good Latin style. Marcus Tullius Cicero was the most influential ancient Roman prose author. Medieval knowledge of his works focused primarily on his philosophical writings. For Petrarch, Cicero continued to be conceived primarily as a wise philosopher. Petrarch also admired Cicero's Latin style, but he made no attempt to purge his own Latin of words and usages not found in Cicero's works. Yet his discovery of Cicero's orations and personal letters initiated a major shift in the perception of the Roman author. These orations and letters revealed that the Cicero whom Petrarch had revered as a moral philosopher interested only in wisdom and virtue was also an ambitious politician eager for power and fame. In the early 15th century, humanists also found manuscripts of Cicero's mature works on rhetoric.
Thus the image of Cicero changed from that of scholarly moral philosopher to that of ambitious statesman, eloquent orator, and supreme master of Latin style. By the beginning of the 15th century, his reputation as the unquestioned authority for all questions of Latin style and vocabulary was growing rapidly. This stress on Cicero as the perfect model for writing Latin was the foundation of what later came to be called Ciceronianism. The early "Ciceronians" did not utterly reject Latin words and grammatical constructions found in other ancient authors, but following Cicero whenever possible seemed the safest way to attain an excellent style.
This emergent Ciceronianism did not pass unchallenged. Lorenzo Valla, himself one of the most brilliant Latinists of his time, caused a scandal when he openly declared that the recently discovered rhetorician Quintilian was a better guide to good Latin than Cicero. In the later 15th century, the Florentine humanist Angelo Poliziano criticized those who attacked his writings as insufficiently Ciceronian. Like Valla, he practiced a consciously eclectic style, looking to other ancient authors in addition to Cicero for models and not hesitant to accept words and structures never found in a known work of Cicero.
The Venetian scholar Pietro Bembo in 1512 argued that Cicero ought to be the model for all who wanted to write good Latin. The humanists at the papal curia in Rome, who made their reputations and their professional careers as experts in classical Latin, were notoriously devoted to a narrow and restricted brand of Ciceronianism. As the influence of Italian humanism spread across the Alps, some natives of northern Europe also began judging Latin style according to Ciceronian models. The young Netherlander Christophe de Longueil spent years among the Ciceronians at Rome and became a sharp critic of contemporary authors who did not write Ciceronian Latin. Other northerners, however, resented the Italians' claim to a monopoly on good style. Their most eloquent spokesman was the Dutch humanist Erasmus, whose dialogue Ciceronianus (1528) made Longueil a particular target of criticism. Erasmus humorously treated Ciceronianism as a disease needing to be cured. In a more serious vein, he defended a model of good Latin that was far less narrow. While he admired Cicero, his own preferences among modern Latinists were those who had adopted an eclectic style, such as Valla and Poliziano. Erasmus' main argument was that because society had changed greatly since ancient times, language must be adapted to express new realities — in particular, the religious change from Roman paganism to Christianity. Accompanying his criticism of the Italian Ciceronians was his conviction that most of them, especially the arrogant curial secretaries at Rome, had very little real religious spirit and in practice lived, thought, and wrote like pagans. A sharp controversy followed the publication of Erasmus' book.
Despite such criticisms, Ciceronianism not only survived but grew in the middle decades of the 16th century. In 1535 Mario Nizzoli published a dictionary of Ciceronian words to guide those who wished to avoid any non-Ciceronian terms. Probably because the practice of defining Cicero as the standard was more easily teachable to students than Erasmus' eclectic style, which depended on a sophisticated taste that few writers possessed, Ciceronianism dominated (and still dominates) the teaching of Latin. Cicero's works were used as school-books. Protestant educational reformers like Philipp Melanchthon at Wittenberg and Johann Sturm at Strasbourg, as well as Catholic educators in Italy and Spain, upheld Ciceronian standards, and the Jesuit order, which became a major force in Catholic education, officially adopted Ciceronian standards in its schools.
Historical Dictionary of Renaissance. Charles G. Nauert. 2004.