In 1536 he obtained a Chair in Humanistic Letters for three years at the University of Pavia: Andrea Alciati was his colleague there, and he wrote his first Orations and the first draft of the three books of Schola, sive De Perfecto Grammatico (not published until 1555).
He described the perfect Grammaticus as an orator who takes the classical foundations of Cicero and Quintilian to inform a contemporary embodiment of the humanist professor, one who dignifies his profession through full responsibility towards his role as educator and cultural guide.
His renown as professor was tied to his anti-Catholic stances: as a result Pope Paul III demanded his removal from the University.
His admiring students accompanied him to his alternative lodgings in the city to defend him from possible attack.
The Senate of Pavia, fearing a threat of excommunication from the Church, succumbed and in 1539 licensed Curio to leave the Duchy.

He next went to Venice, where he attended the French Ambassador to the republic, the Bishop of Montpellier.
To him he dedicated the Aranei Encomion, a short tract treating the fable of Arachne as an allegory of the Church and Holy Wisdom, published in Venice in 1540.
In Lent he is likely to have heard the preaching of Bernardino Ochino.
He became the companion of the Augustinian mendicant Giulio da Milano, a secret protestant convert.
Giulio, who had preached justification by faith alone, was arrested in 1541, and Curio, identified as his close associate, departed abruptly for Ferrara.
There his friend Pellegrino Morato, preceptor in the court of Este, recommended him to Duchess Renata, wife of Ercole II d'Este.
He remained briefly, forming a friendship with Morato's young daughter Olympia Fulvia Morata, with whom he maintained a lifelong correspondence.
In 1536 he obtained a Chair in Humanistic Letters for three years at the University of Pavia: Andrea Alciati was his colleague there, and he wrote his first Orations and the first draft of the three books of Schola, sive De Perfecto Grammatico (not published until 1555). He described the perfect Grammaticus as an orator who takes the classical foundations of Cicero and Quintilian to inform a contemporary embodiment of the humanist professor, one who dignifies his profession through full responsibility towards his role as educator and cultural guide. His renown as professor was tied to his anti-Catholic stances: as a result Pope Paul III demanded his removal from the University. His admiring students accompanied him to his alternative lodgings in the city to defend him from possible attack. The Senate of Pavia, fearing a threat of excommunication from the Church, succumbed and in 1539 licensed Curio to leave the Duchy.
He next went to Venice, where he attended the French Ambassador to the republic, the Bishop of Montpellier. To him he dedicated the Aranei Encomion, a short tract treating the fable of Arachne as an allegory of the Church and Holy Wisdom, published in Venice in 1540. In Lent he is likely to have heard the preaching of Bernardino Ochino. He became the companion of the Augustinian mendicant Giulio da Milano, a secret protestant convert. Giulio, who had preached justification by faith alone, was arrested in 1541, and Curio, identified as his close associate, departed abruptly for Ferrara. There his friend Pellegrino Morato, preceptor in the court of Este, recommended him to Duchess Renata, wife of Ercole II d'Este. He remained briefly, forming a friendship with Morato's young daughter Olympia Fulvia Morata, with whom he maintained a lifelong correspondence.
Celio Secondo Curione