We know that we each have a guardian angel whose task it is to watch over us, protect us from spiritual harm (and, in some cases, physical harm), nudge our consciences when we consider doing wrong, and so forth. Our guardian angels are always at our side.
This raises a question, however. Angels do not have bodies; they are pure spirits. Since they have no physical bodies, they can't be said to be in any particular physical place in a physical way, e.g. "at my side." So what does it mean to say that my guardian angel is always present with me, "at my side"?
St. Thomas gives us the answer. He tells us that an angel's relation to place is not according to physical presence but rather according to "contact of power" (ST I, q. 52, a. 1). In other words, an angel is said to be located wherever it is that the angel is working or turning its attention.
Let's put these two things together: if an angel is said to be in a place according to its directing its power to that place, then if our guardian angel is always with us, that means that our angel is always working on us, attentive to us, directing its power to us. Your guardian angel is constantly working for your spiritual well-being.
A beautiful and consoling thought, made possible by a truth cultivated by "dry scholastic speculations."