Since the beginning of Advent, Rae and I have been attending Vespers with the local Benedictines. This evening, as we chanted the Psalms, I was struck by the way that the chant subtly coloured my interpretation of them. And it occurred to me that perhaps this one of the chief reasons it is so difficult for moderns to sympathize with the thought of a St. Thomas or a St. Anselm.
If we read the Psalms we probably do so silently. If we hear them sung, it is likely in a “modern” style. (Which might date back a couple of decades or a couple of centuries depending on the church.) Just as different meanings can be brought out of a text by readers with their distinctive emphases, so too can different forms of music cause us to see the text differently.
The lives and thought of the great medieval theologians like Anselm (a Benedictine), Aquinas (a Dominican) and Bonaventure (a Franciscan) were formed by the process of praying the Divine Office with their brethren. The chief components of the Office are the Psalms and Canticles which they would have chanted together.
All that being said, here is my suggestion. If you want to more easily enter into their thought-world, try to pray as they prayed, keeping the Hours and chanting the Psalms and Canticles, preferably with a community. Theirs is a “kneeling theology,” and to get their perspective it helps to kneel with them.