How did St. John Vianney become a priest?

Not to be flippant, but by the grace of God. When St. John Vianney applied for, and started in the seminary, no one had any doubt that he had a vocation to the priesthood However, he was of only average intelligence, and his mind was not subtle, or flexible: he had an extremely difficult time in the seminary, repeatedly failing exams and never really becoming proficient at Latin. Also, he was conscripted into the service in the middle of his seminary education.