It is not uncommon for the Principle of Complementarity to be invoked in either Science or Philosophy, viz. the ancient oriental philosophy of Yin and Yang whose symbolic representation is portrayed on the cover of the book. Or Niels Bohr's use of it as the basis for the so-called Copenhagen interpretation of Quantum Mechanics. This book arose as an outgrowth of the author's previous book entitled "Knots, Braids and Moebius Strips," published by World Scientific in 2015, wherein the Principle itself was discovered to be expressible as a simple 2x2 matrix that summarizes the algebraic essence of both the well-known Microbiology of DNA and the author's version of the elementary particles of physics. At that point, the possibility of an even wider utilization of that expression of Complementarity arose. The current book, features Complementarity, in which the matrix algebra is extended to characterize not only DNA itself but the well-known process of its replication, a most gratifying outcome. The book then goes on to explore Complementarity, with and without its matrix expression, as it occurs, not only in much of physics but in its extension to cosmology as well. Sample Chapter(s) Front Matter 1. Introduction: Complementarity as a Principle 2. Deoxyribonucleic Acid, The Molecular Ladder to Life on Earth 3. Alternative Model Taxonomy Contents: Preliminaries: Introduction: Complementarity as a Principle Deoxyribonucleic Acid, The Molecular Ladder to Life on Earth Alternative Model Taxonomy The AM/DNA Comparison The Signature of Complementarity; Replication Unleashed A (Particular) Connection to Chemistry Some Basic Physics: Dynamics Thermodynamics Energy-wise Comparison of Two Exercises Maxwell's Equations and the Electromagnetic Field Spacetime and The Ethereal Road to Relativity Noether's Theorem and Gauge Theory General Relativity and the Geometry of Spacetime: General Relativity Differential Geometry and The "Action Enigma"; an Application An Authoritative Perspective And an Inference Thereof An "Indigenous Parallel" to the Higgs Undulation (or Undulatority) Another look at Our "Indigenous Higgs Model" Quantum Mechanics and the Significance of Scale: Introducing Max Planck and the Quantum Quantum Mechanics, Phase 1 Phase 2; Through the Looking Glass! Quantum Mechanics, Radar and the Significance of Scale The Fourier Transform and the Convolution Theorem Nonlocality, Entanglement, and complementarity Spin, Spinors, and the Pauli Connection PAM Dirac, Mixmaster Extraordinaire Statistical Mechanics Some Additional Alternative Model Topics: "Deuteronomy" and Isospin Invariance Cosmological Complementarity Gurule Loops Summary and Conclusions: Recapitulation Linking Complementarity and The Meaning of "Is" Readership: Undergraduate and graduate students in Mathematics and Physics.