As Cat moved into the philosophy sections he can see someone already there, and she is even reading a book! Hunching over he confirms the title of the book she's reading, being that one book where his thinks he understands but probably doesn't. And she's looking at one of those diagrams that he definitely doesn't.
Standing beside her to analyze the two-page visualization of one of the schools of thought of influences on a person's Aura and Semblance. In the middle of the left side is your Soul, the culmination of one's being. On the right side is you as a person, an intuitively mundane concept. Then at the top of the left side are an array of experiences which is mirrored on the right. They are pointed at the respective centers of its graph like it is an input/output flowchart, but their outputs are drastically different: on the person's side are a collection labeled 'feelings' and is fed back into 'experience' on both sides, which is mostly true, as what one thinks does have an impact on what course of action would they take and therefore the outcome of them; on the Soul side, however, the output was Aura, being a single block that Semblances develops from, and they are sporadic at that. Which of course feeds into 'experience' again and the cycle began anew. This is the idea that everyone is the same at birth and experiences shapes who they are and what they do recursively.
Actually, didn't Catalina just explained it perfectly? It seems like he subconsciously made an analog with a certain something he is familiar with that he didn't know the last time he read it. A device that outputs vastly different results even with small differences in input, isn't that a pseudorandom number generator? But the semblance remains largely the same once it is discovered... "Ah!" Got it! A procedurally generated map! He finally got the gist of the confusing side of this graph and is pretty satisfied. Now just to organize his words and spell it out...
Oh, and she's standing right next to Prism the whole time, his curiosity having overwhelmed his sense of personal space.