Bhagavad Gita, Chapter 14, Verse 22

The Deity said: He who hates not the appearance of light, the effect of Sattva, activity the effect of Rajas, and delusion the effect of Tamas, in his own mind, O Pândava, nor longs for them when absent.

Real neutrality is described here as working in both directions, no aversion and no craving either.

Not hating illumination or activity even when absent, and not resenting delusion even when present, shows a real evenness that doesn't depend on which force happens to be active. Balance here holds steady regardless of circumstance.