Although it dates me to admit it, I was a high school student during the Second Vatican Council.
In our daily religion classes at Aquinas High School in La Crosse (yes, we had daily classes all taught by priests at that time), we studied the documents of that council.
One of those documents had a special impact on me. It was the Dogmatic Constitution on the Church also known by its Latin title, Lumen Gentium.
This document — promulgated by Blessed Paul VI on November 21, 1964 — talks about the hierarchical structure of the Church, including the role of bishops, priests, deacons, and Religious. It also has a full chapter on the laity, which was especially interesting to me 51 years ago.