Lewis opens the introductory chapter of this book with the statement that it is not a work of scholarship; but simply "the thoughts…to which I found myself driven in reading the Psalms." He then gives a brief history and analysis of the Psalms, the main point of which is that they are poems and must be read as such in order to be understood, followed by an explanation of the primary poetic characteristic of the Psalms – parallelism.
The next eight chapters address recurrent ideas or phrases in the Psalms, the original meaning of which may not be readily comprehended by modern English readers – judgment, cursings, "sweeter than honey," praise, and others. Lewis examines the Hebraic thought behind these concepts and leads us to a better understanding of what they must have meant in the minds of the writers and early readers, as well as what application they may have for us today.
In the final three chapters, Lewis takes on what he considers the more difficult task of exploring the second or hidden meanings in the Psalms - those passages which may be interpreted, from the vantage point of many hundred years, as prophetic or allegorical. His position is that these occurrences are neither coincidence nor supernatural prevision; rather in these cases "the later truth (which the speaker did not know) is intimately related to the truth he did know; so that…he was in touch with that very same reality in which the fuller truth is rooted…we are not foisting on [his words] something alien…[but] prolonging his meaning in a direction congenial to it."
One of the many things I love about Lewis is that he never claims to be – in fact takes great pains to insist that he is not – a theologian. His approach is that of a fellow-pupil "comparing notes, not presuming to instruct." And while he is widely known today as a great apologist, he points out that this particular book is not an apologetic work: "A man can't be always defending the truth; there must be a time to feed on it."