Today is the Feast of St. Bonaventure of Bagnoregio, Doctor of the Church. From his Breviloquium (Part VI, Chapter 3):
Since this army [of the Church] consists of elements that are subject to weakening, in order that the ranks be perfectly and permanently strengthened, it needs sacraments to fortify, relieve, and replenish its members: to fortify the combatants, relieve the wounded and replenish the dying. Now, a fortifying sacrament strengthens either those just entering the combat, and this is Baptism; or those in the midst of the fray, and this is Confirmation; or those who are leaving it, and this is Extreme Unction. A relieving sacrament alleviates either venial sin, and this is the Eucharist; or mortal sin, and this is Penance. Finally, a sacrament that replenishes does so either on the level of spiritual existence, and this is...Orders, which has the function of administering the sacraments; or on the level of natural existence, and this is Matrimony, which replenishes the multitude of humanity in their natural existence, the foundation of everything else....
And so Baptism is designed for those just entering the fight, Confirmation for those engaged in combat, the Eucharist for those refreshing their strength, Penance for those rising from their sickbeds, Extreme Unction for those who are departing, Orders for those who break in the new recruits, and Matrimony for those who provide these recruits. And so it is evident that the sacramental remedies and armaments are both sufficient and orderly.
[Bonaventure, Breviloquium, Monti, ed., The Franciscan Institute (Saint Bonaventure, NY: 2005), pp. 220-221.]
Bonaventure was the second Doctor of the Church (after Aquinas) to be explicitly designated as such by a Pope. (The first eight Doctors of the Church achieved and established the title by a much more piecemeal process of liturgical development; their title was extended to Aquinas and Bonaventure by papal authority.) I've noted before that Bonaventure's real name was Giovanni di Fidanza -- 'Bonaventura' is a nickname that means 'Good Fortune'. We don't know why he was nicknamed Lucky, but Bonaventure himself tells us that as an infant he was cured of an illness by St. Francis of Assisi, and late tradition suggests that he was given the nickname by St. Francis himself.