1549, Du Belle published the famous declaration "Defending and Promoting French" on behalf of Seven Star Poetry Society. This manifesto was written by Tudor Bell, a poet of the Poetry Society. The general idea of the declaration is as follows: French national language can be comparable to Greek and Latin, and literary masterpieces can be written in French, but French should be made as colorful as possible; Advocate imitation of Greek and Latin writers, at least in poetry, but do not advocate simple translation of ancient works; All kinds of popular poetry genres in France are not worth keeping, and should be replaced by ancient poetry meter; A poet should not only master the skills of writing poems, but also have inspiration from heaven.
In the same year, he published his first collection of works, Olive Collection, which included 50 sonnets. This collection of poems is a very outstanding imitation work. It is the Collection of Olives that introduced sonnets into France.
During his stay in Rome, he had the opportunity to appreciate the remains of the ancient Roman empire and imagine its glory and subsequent decline, which led to the birth of a collection of poems, Missing Rome. Another sonnet, Regrets, describes contemporary Rome, which is his true feelings of disappointment and depression. In the process of describing the Pope's court, customs, cities and people, his superb satire can be perfectly reflected.