Nah, I subscribe to the position that mantras aren't necessarily semantic (well, they can be, but those are particular) I think it's more about the sound or repetition itself, since repetition is one way of really effectively 'purifying' your mind of thoughts or speech. I don't use mantas much, but I've been pretty into Dzogchen lately and they use the seed syllable 'A' (as in "father") as symbolic for the primordial state/rigpa, because it's the most unfabricated or uncontrived sound. There are also some meaningful symbolism in terms of the Tibetan writing system, where the written letter 'A' in Tibetan is the template or progenitor of all other graphemes. It's just a relative representation of something a lot more fundamental or important, though (the direct experience of emptiness itself in this case). So sometimes they are fairly symbolic, but in my experience it's in kind of a loose, abstract, or aesthetic way, like "a finger pointing at the moon isn't the moon", that sort of thing.
I'm glad you had success with it. One thing about meditation that is kind of hard to understand at first, is that it isn't necessarily about concentration in a conventional sense. A lot of the time I think it's better likened to 'undistractability'. That may seem to be saying the same thing at first, but the attitude that is usually conveyed by either idea is different. Instead it's rather that our mind tends to get snagged on things, habitual thoughts ("I wonder what I'll have for supper today?"), or passions, or even like the movie you watched earlier. You're just practicing the ability to notice these thoughts, and let them go so they don't just hold you hostage until they run their course. It's more like a sort of freedom, or simply 'not being distracted'; as opposed to being 'concentrated'. If you remain 'not distracted' for long enough, your mind will naturally collect itself on its own.
By the time I'm done with school, I'll be dead. 2-7 more years, here I come.
