I have lots of favorites:
“Faith and reason are like two wings on which the human spirit rises to the contemplation of truth; and God has placed in the human heart a desire to know the truth—in a word, to know Himself—so that, by knowing and loving God, men and women may also come to the fullness of truth about themselves.” Pope John Paul II, Fides et Ratio
“Most modern freedom is at root fear. It is not so much that we are too bold to endure rules; it is rather that we are too timid to endure responsibilities.” GK Chesterton, What’s Wrong With the World
“There must, whether the gods see it or not, be something great in the mortal soul. For suffering, it seems, is infinite, and our capacity without limit.” CS Lewis, Till We Have Faces: A Myth Retold
“Everyone…lives, above all, for love. The ability to love authentically, not great intellectual capacity, constitutes the deepest part of a personality. It is no accident that the greatest commandment is to love. Authentic love leads us outside ourselves to affirming others: devoting oneself to the cause of man, to people, and, above all, to God. Marriage makes sense…if it gives one the opportunity for such love, if it evokes the ability and necessity of such loving, if it draws one out of the shell of individualism (various kinds) and egocentrism. It is not enough simply to want to accept such love. One must know how to give it, and it’s often not ready to be received…” from a letter to “Teresa”, Karol Wojtyla (later, Pope John Paul II) (Dec. 1956)