I utilize a lot of different resources when I'm writing a story. As I clean up my notes and arrange my scattered sources into notebooks, I often come across random notes--highlighted passages or notes that I've written to myself--that take on a special meaning within the context of the themes I want to express.
I'll share a few of these from time to time, just to let you in on that "where do you get your ideas" question.
When I create magical systems, I like to fall back on religious texts already in existence. Saves me a lot of work, especially when someone more intelligent than me has gone to the trouble to write all this information down. I came across this particular passage when I was looking into the symbolic value of the heart.
There [the heart] is conceived of as central in the activity of the rsis, those seers who intuitively perceive the divine and express it in hymns. The heart is the secret place of their inspiration, where hymns are prepared to offer the gods, but it is also the critical authority that monitors the hymns' value. The heart thus becomes the place of divine vision, which is only given by grace to those who practice self-renunciation. It is understood that the heart's knowledge is satya, real and true, since it alone can enable one to pass from the unreal and the illusory to the real. Such knowledge is transformative, for it discovers, by means of the heart, the divine immanence within man. In bhakti, the heart is the seat of an aspiration to join the god and the center of a desire that "binds man at the level of his heart." Man should also reject the desire of natural and illusory realities in favor of the enjoyment of bliss and union with brahman. It is necessary to clear this heart by way of renunciation in order to become "a polished mirror" in which the god can be reflected.