Why had Leopold I originally been prepared for a career in the church?

Leopold I was originally destined for a career in the church because he was the second son of Ferdinand III and his first wife, Maria Anna.1

In the tradition of the time, younger sons of ruling houses were frequently prepared for ecclesiastical roles rather than the throne. Consequently, Leopold received a careful education tailored to this path, becoming fluent in Latin, Italian, and Spanish, and developing a deep sense of personal piety that remained a defining trait throughout his life. He only became the heir apparent to the Austrian Habsburg lands following the unexpected death of his elder brother, Ferdinand IV, in 1654.1