When did the use of formal, seminary-type education begin and why?

**When did it become the norm for church leaders to get a formal Christian education and why did that process begin?** When I say formal education I'm **not** talking about the mentor/mentee style that Jesus did with his disciples. I'm talking about the following scenario: - A person independently enrolls in a Bible School/Seminary/Divinity school - They get a degree - They apply for pastor jobs and get hired as a pastor somewhere The reason I ask is because the aforementioned process isn't implied anywhere in scripture. The idea of it had to have come from somewhere and for some reason. --- Similar to this question , but I'm not asking whether or not this practice is supported by Scripture—I'm asking when it started and why it started.