Other than the mathematical term differential, do you know what differentials are? How about tired and rested as in, “I am so tired of dealing with this day; I need to go to sleep, and “I slept so well, I am ready for the challenge of this day.” Differentials are the only way we recognize anything in the science of existentialism as in hard vs. soft, light vs. dark, real vs. unreal, good vs. evil. One might consider many differentials, even righteous vs. unrighteous. What does that have to do with my sleep? Read “The Ecstasy of my Dream.” See http://tjginn.com/publications for discounts and links.