In principio

IN PRINCIPIO. At the beginning this is frequently used in citations; as Bac. Ab. Legacies, in pr.

A Law Dictionary, Adapted to the Constitution and Laws of the United States. By John Bouvier. Published 1856.
References in classic literature ?
"True, no doubt," said Don Fernando, "for which reason, Senor Don Quixote, you ought to forgive him and restore him to the bosom of your favour, sicut erat in principio, before illusions of this sort had taken away his senses."