In 1994, when Banner of Truth republished Geerhardus Vos’ 1922 collection of sermons titled Grace and Glory, which originally contained six sermons, they added 10 more to the reprint. Sinclair Ferguson explains:
In possessing a copy of Grace and Glory the reader has in his or her hands a book of sermons which are almost as rare as they are remarkable. Not only so, but in addition to the six sermons which originally constituted the volume Grace and Glory the present edition includes a further nine sermons which Vos preached in the Chapel of Princeton Theological Seminary between 1896 and 1913, as well as an undated exposition of Ephesians 2:4-5 translated from Dutch. This additional material has been provided to the publishers by James T. Dennison, the Librarian of Westminster Theological Seminary in California and the editor of the journal Kerux, in which the bulk of has already been published. Mr. Dennison originally uncovered Vos’s personal sermon book in 1971 in the Heritage Hall Archive of Calvin Theological Seminary and transcribed the material. As heirs of his labours the publishers are also indebted to the Heritage Hall Archive of Calvin Seminary for the privilege of reproducing the material in this more permanent form.
One of those additional sermons is titled “Songs From the Soul,” based on Psalm 25:14: “The secret of the LORD is with them that fear him; and he will shew them his covenant.” In this sermon, Vos speaks to the experimental piety of the Psalter in eloquent terms (pp. 169-171).
The Psalter is of all books of the Bible that book which gives expression to the experimental side of religion. In the law and the prophetic writings, it is God who speaks to his people; but in the Psalter we listen to the saints speaking to God. Hence the Psalter has been at all times that part of Scripture to which believers have most readily turned and upon which they have chiefly depended for the nourishment of the inner religious life of the heart. I say that part of Scripture and not merely that part of the Old Testament, for even taking the Old and New Testament together the common experience of the people of God affirms that there is nothing in Holy Writ which in our most spiritual moments — when we feel ourselves nearest to God — so faithfully and naturally expresses what we think and feel in our hearts as these songs of the pious Israelites. Our Lord himself, who had a perfect religious experience and lived and walked with God in absolute adjustment of his thoughts and desires to the Father's mind and will, our Lord himself found his inner life portrayed in the Psalter and in some of the highest moments of his ministry borrowed from it the language in which his soul spoke to God, thus recognizing that a more perfect language for communion with God cannot be framed.
Undoubtedly it is in the Psalter that the specific work of inspiration which the Holy Ghost performs in inditing the Scriptures and the more general task which he carries out in sustaining, directing, stimulating and guiding the religious thoughts and aspirations of believers are most closely united. Inspiration for the disclosure of truth is not always accompanied by the subjective appropriation of the truth in a saintly experience (a Balaam and a Caiaphas were among the prophets); but nevertheless it remains the more natural and ordinary procedure of God that the instrument through which his truth is brought to man should be a mind in intimate touch with his own; a mind responsive to that personal revelation of God himself which lives and throbs in the truth. And consequently we see that the great prophets (like a Moses, an Isaiah or Jeremiah) appear at the same time as the outstanding examples of a wonderfully rich and tender religious intercourse with God. But in the Psalms we can more clearly than anywhere else observe the interaction of these two things: supernatural reception of the truth and spiritual nearness to God. Possibly the fact that in David's case the prophetic disclosures of truth that he received were so vitally connected with his own life and destiny may have something to do with the presence of this feature in the Psalms, whereas the other prophets sometimes stood more or less apart from the development of things to which their words applied. And then the prophets, of course, in many instances spoke to and for the nation collectively, whereas in the Psalter it is the individual soul which comes face to face with God.
Hence the lessons and encouragements which we obtain from other parts of the Old Testament are frequently drawn indirectly by a process of inference, for which we are not always in the right frame of mind and the proper spiritual mood. But the in Psalms, whatever our mood, whether we are exultant or downcast, vigorous or weary, penitent or believing, we can always find our hearts mirrored there. It needs no process of reasoning to make their sentiments our own. Here the language of the Bible comes to meet the very thoughts of our hearts before these can even clothe themselves in language and we recognize that we could not have expressed them better than the Spirit has here expressed them for us. At first sight, this may easily seem strange to us when we remember that the the psalmists lived under the conditions of a typical and preparatory dispensation; that on many points they saw through a glass darkly, whereas we, who live in the full light of the complete gospel, see face to face. But for the very reason that the Psalms reflect that experimental religion of the heart, which is unvarying at all times and under all circumstances, we need not greatly wonder at this. The influx of the divine light, whether more or less strong, must always produce the identical effect of joy, hope and peace in every soul to which it comes. The well at which we drink may flow more abundantly than that at which the psalmists drank, but the experience of thirst, of drinking and of satisfaction must still be the same as it was in the time of David.