The third piece in the collection is "Psalmsong", which is based on moods created by Psalm 30, which is the famous text that talks about: "weeping may tarry for the night, but joy comes in the morning".
It is a slow-moving mediation that begins on the Solo strings, before expanisvely increasing to warm 8' and 4' stops.
A sort of "duet" begins the last section, which uses the Violone 16' and Viola 8' in the Pedal, with the obligato being played high on the Flute Harmonique (with tremulant" on the Solo.
A colorful and soft final cadence, along with the 32' Open in the Pedal bring the piece to a conclusion.
This piece is an arrangement of the central portion of Utterback's "Fantasy for Organ", which I have never heard... ;-)