What does と mean in と思います, と言う, and と見る？ means "The light which is called Love", but why is used? Why does mean "to see" but means something like "it was judged to be"? What function is serving?

is frequently used as a "quoting" particle, for thoughts or for speech.

is "I think **that** ", with the thought being "quoted" coming in the . Similarly, you can have (I think **that** ), (I believe **that** ), and similar examples.

Likewise, used with the kanji means "I (will) say **that** ".

However, used without the kanji tends to indicate that the from which it is derived is acting grammatically, and is thus often better translated as "that is" in these circumstances. But "that is called" is usually fine at getting the essence of the meaning across, if a bit unnatural. There are a tonne of more complex grammatical constructions which use (e.g. , , , etc.), so be careful as to what proceeds and follows in general.

Extending the above examples in the same way, is more along the lines of "see **that** " or "regard **as** " -- it's a somewhat more abstract sense of "seeing", e.g. understanding a thought, hence you mark it with the quoting particle .