Interesting question. In Jain philosophy, a few points help explain this apparent paradox:

• Existence (stitva) and non-existence (nastitva) are often relative. For any phenomenon, there can be aspects that are real from one perspective and not from another. This is a core idea of anekantavada (the doctrine of many-sided truths).

• Light and darkness are also relative. Darkness isn’t a substance in Jain thought; it is the absence or hindrance of light. Where there is light, darkness cannot prevail. Darkness can only exist as a contrast to light, or in regions where light is obstructed or incomplete.

• In Jain metaphysics, everything is made of substances (jiva or ajiva), and the truth about any object depends on the standpoint and the level of description you use. Thus, “there is existence” and “there is non-existence” can both be valid statements when speaking from different naya (aspects) or perspectives.

• A parallel from Jain Dharma: knowledge (jnana) is like light; ignorance (avidya) is like darkness. The goal of spiritual practice is to remove ignorance and realize kevala jnana (omniscient knowledge), which is the true, ultimate light.

• If you’re thinking in terms of light and shade, remember that light can be present in varying intensities and angles, creating illuminated and shaded regions simultaneously. Similarly, truth can have multiple facets, and apparent opposites can coexist in different contexts.

If you’d like, I can share a brief, purified explanation from the Jain texts on anekantavada and the nature of truth, or provide a simple meditation analogy to help internalize this idea.