From Gasparri's Catechism
Gasparri Qurestion 156(156) Who are the Bishops' assistants in the care of souls?
The Bishops' assistants in the care of souls are the priests, especially the parish priests, who are subject to the Bishops according to the provisions laid down in Canon Law.The laity of either sex can most effectively help the Church in her ministry as well by their own personal influence which may affect the spiritual goods of their neighbors, as also by what is termed "Catholic action," so earnestly recommended by the Supreme Pontiff, and so clearly referred to by St. Paul, Phil. iv, 3. The laity should, if they can, join in "Catholic action," for by such loyal cooperation with their Bishops on the lines laid down by the Apostolic See, they will be materially forwarding the ideal set before us by the Church, in other words the triumph of the Kingdom of Christ and the salvation of the human race.
From Gasparri’s Catechism: (155) What is the power of order?
The power of order is the power of performing sacred functions, especially of ministering at the altar; by the Sacrament of Holy Order it is conferred on the sacred Hierarchy, especially on the Bishops. Since this power has for its main object the sanctification of men's souls through divine worship and the administration of the Sacraments, it comprises what is generally known as "the care of souls."
The power of Order, is for its legitimate exercise, subordinated to the power of jurisdiction.