I risk a rather straightforward interpretation of the quote.
If we read the sentence metaphorically, it tells a story of a person (referred to as he but I guess it may be anybody, the general audience) who lived without love and also without the metaphorical light. (LOVE = LIGHT).
Important is also the aspect of darkness. Darkness is generally associated with negative things (lack of vision, lack of orienatation). This quote, presumably, equates light with (some kind of) knowledge.
So, LOVE (LIGHT) gives people an incentive to learn about the world and gain knowledge (the opposite of darkness).
Translation would be something along the lines of ''Ten, kogo dotyka milosc, nie kroczy w ciemnosci''.
