What are the quotations? They are, for the most part, expressions of truth, as their authors have come to see that truth, in compact and vivid language. They can be read as literature, but like all great literature, they require that the reader go further and consider the truth presented in the larger context of our faith, our knowledge of God, Scripture, and our experience of the world.
As literature, the quotations have a remarkable similarity which began to stand out to me as I worked with them. Many of the really fine, memorable quotations employ parallelism, symmetrical patterns in successive phrases that mirror each other. The following quotation exhibits two instances of a parallelism exhibiting reversal, formally called a chiasm
, which abounds in Scripture:
Do not pray for tasks equal to your powers. Pray for powers equal to your tasks. Then the doing of your work shall be no miracle, but you yourself shall be the miracle.
... Phillips Brooks (1835-1893)
The following quotations exhibit an inversion parallelism that makes them very memorable:
Jesus Christ is a God whom we approach without pride, and before whom we humble ourselves without despair.
... Blaise Pascal (1623-1662), Pensées 
He is no fool who gives what he cannot keep to gain what he cannot lose.
... Jim Elliot (1927-1956), missionary, martyr
Most memorable of all, to me, are those that employ a reflexive symmetry:
He who cannot forgive breaks the bridge over which he himself must pass.
... George Herbert (1593-1633)
The Man Christ Jesus has the decisive place in man's ageless relationship with God. He is what God means by 'Man'. He is what man means by 'God'.
... J. S. Whale (1896-1997), Christian Doctrine 
The reader will find numerous examples of these patterns in CQOD.
The value of quotations lies not only in their compactness, but in their capacity to be absorbed and retained. The foregoing examples make it clear that parallelism, and the other literary devices that abound in this collection, serves to enhance that value. This principle extends to all communications. But I suggest that the truth will often contain this kind of symmetrical presentation, not because symmetry is of value in itself, but because the truth of God is, in the long run, perfectly black and white, in a way that our earthly judgments seldom are. Somehow, the symmetry is a mark of His presence; perhaps not an infallible one, but it is rarely missing.
Scripture abounds with such literary devices. This is particularly true in the Psalms and the other examples of Hebrew poetry in the Bible. No doubt, this is the wellspring from which the best styles of subsequent literature have flowed. But there is a truth that is deeper yet.
All of creation reflects the perfect order of the mind of God, with its infallible epistemology, its exhaustive detail, and its single, unified intent that suffuses every cause and effect. I am reminded of the old introit,
Spiritus Domini replevit orbem terrarum.
“The Spirit of God fills (up) the earth.” The word “replevit,” from which we get our words “replenish” and “replete,” means to “fill unto satisfaction.” There is always enough of the Spirit of God, in whatever portion of the world one is working in or on, to see Him in His work, to serve Him, and to praise Him.
And in this filling of the world with God’s Spirit, we meet Him, Whose truth confounds us: Holy God, sinful man; an antithetical symmetry that saturates the entire relationship. Yet those who are led by the Spirit of God are the sons of God. (Rom. 8:14) It is into this fearful Presence of ferocious love and blinding vision that we are cast. All
turn away, but the sons and daughters come back. No one can report of it except in metaphors and paradoxes. But afterwards, we know that it is YHWH Himself who is the source of language, the origin of meaning, and the author of existence, Whose word is truth. Thus beauty, power, and symmetry of language and thought are His ideas, and He has placed in our minds the hunger for His truth and the recognition of its signs.