The Euler-Lagrange equation is shown here to be so comprehensive, in small and large scales, that is likely to explain whatever we find at any scale, including dark matter, dark energy, and gravity. The mathematical version is published in a separate (see 14]). This is a more textual version available, publicly, from lectures and student experience. This book, going beyond the epsilons and deltas of Newtonian continuity, fits a graduate students' gap in physics, the Nature-defined channel, which cannot be conveyed mathematically, entirely, thus creating a more complete picture.