“For the Emperor is within the Church, not above it.”

For the Emperor is within the Church, not above it.

Ambrose · Letters, and the funeral orations · NPNF2 X, Letter XXI

Written to Valentinian II in 386, refusing to argue the faith before an imperial consistory. It is the sentence the Western church leaned on for the next thousand years, and Ambrose wrote it to a boy of fifteen whose mother commanded the troops outside his basilica.