Complex sentence: During this early period, the order had three grades of Novice, Minerval, and Illuminated Minerval, of which only the Minerval grade involved a complicated ceremony where the candidate was given secret signs and a password.
Split into simpler sentences: During this early period, the order had three grades of Novice, Minerval, and Illuminated Minerval, of which only the Minerval grade involved a complicated ceremony. In this the candidate was given secret signs and a password.