Light is not only the source of life and the vehicle for manifesting the physical world, but also is a common metaphor for positive emotion and spirituality. We yearn for enlightenment and wait for the redemptive twilight, shed light upon and illuminate difficulties, delight and brighten up someone's day, shine and beam with radiance, and ignite the spark in someone's heart and soul.
The examples from our own tradition are numerous: Moshe encounters a burning bush and his face shines with light; Sinai is ablaze with lighting and fire, and the Mishkan contains the fire of G-d; David ha'Melech sings "in His light we see light" (Tehillim 36:10) and that "light is sown for the righteous" (97:11); and the prophets await the day when the Israel and the entire world will be inundated with light (Yesheyahu 30:26; Zecharia 14:7.)
Torah too is called light - Ner Mitzvah v'Torah Ohr (Mishlei 6:23; also see Tehillim 119:105) Our Sages understood that just as light refracts into different hues so does the Torah split into seventy different facets (Rashi on Shemot 6:9, based on Yirmeiyahu 23:29). Furthermore, just as a candle does not lose its strength by lighting another candle so too a teacher does not lose his wisdom from teaching a disciple (Netziv, Ha'amek she'elah, based on Devarim 33:2).
But light is not merely a metaphor for spirituality. Mystics and survivors of Near Death Experiences see the light, and healers perceive and work with energy. The Torah, too, is not only compared to light - it is light.
The Ramchal (Derech Eitz Chaim) continually reminds his readers that the Torah is Ohr mamash - real and perceivable light. The light from Hashem Himself (Derech Hashem 4:2:5) Accordingly, the Ramchal (4:2:7) takes on Sukkah 28a literally: Yonasan b Uziel would generate enough energy while learning Torah that if a bird would fly over his head it would be burnt. On a lesser leve, it is said that the doctors of Rabbi Akiva Eiger were flabergasted - how could such an old man have so much energy? The secret is that this hidden light (Tanchuma, Parshat Noah 3) gives life (Tehillim 36:10).* This can be compared, l'havdil, to a Qi gong or Tai Chi master who through certain outer and inner meditative movements can generate powerful energy.** The Jewish version of Tai Chi - our ruchniyot - is Torah u'Mitzvot. And through this light the Torah cleanses the mind, heart (Kiddushin 30b), and body (Eruvin 54) of a person.
*Recently a healer in Jerusalem who I am fortunate to know told me that the light he saw in the Torah scroll gave him renewed pure energy after a particularly dark and difficult patient.
**Attention has particlarly been drawn to the parallels between the placement of Tefillin and Acupuncture points (I once heard that Rebbe Nosson in Likutei Halakhot discusses this). See here and here.