The philosophy that negative is the oppisite of positive but it's only lacking the positivity.

In their orgins, Satan (as Lucifer) was good, but when he rebelled with ⅓ of the angels, he lost this goodness. So there is really no evil essence, it is just the absence of goodness. Just as there is no cold energy in physics, there is only a lack of warm energy, or there are no particles of darkness, but a given dark abyss does not have even a single particle of light. Even in primitive and even primitive-sounding languages, the oppisite of, for example, large was the word being simply UNlarge.