His first work, a commentary on Seneca's _De Clementia_, witnesses his wide reading, his excellent Latin style, and his ethical interests.
It was apparently through the humanists Erasmus and Lefevre that he was led to the study of the Bible and of Luther's writings.

Probably in the fall of 1533 he experienced a "conversion" such as stands at the head of many a religious career.

A sudden beam of light, he says, came to him at this time from God, putting him to the proof and showing him in how deep an abyss of error and of filth he had been living.

He thereupon abandoned his former life with tears.
In the spring of 1534 Calvin gave up the sinecure benefices he had held, and towards the end of the year left France because of the growing persecution, for he had already rendered himself suspect.
After various wanderings he reached Basle, where he published the first edition of his _Institutes of the Christian Religion_.

[Sidenote: Institutes of the Christian Religion, 1536] It was dedicated, like two of Zwingli's works, to Francis I, with a strong plea for the new faith.
It was, nevertheless, condemned and burnt publicly in France in 1542.
Originally written in Latin it was translated by the author into French in 1541, and reissued from time to time in continually larger editions, the final one, of 1559, being five times as bulky as the first impression.