William Shakespeare's Sonnet Philosophy Volume 4 (Second Edition 2019 Part 1 explains how the combination of the logic behind Charles Darwin's biology, Ludwig Wittgenstein's language philosophy, Stephane Mallarmé's symbolic poetry, and Marcel Duchamp's mythic logic of art each provide a component that Shakespeare's comprehensive and consistent philosophy coordinates and completes. Part 2 examines the work of a number of thinkers to show how they are compromised by an inability to determine Shakespeare's nature-based logic. There are essays on Sigmund Freud/Carl Jung, James Joyce/T. S. Eliot, Stephen Booth/Helen Vendler, and Friedrich Nietzsche/Ludwig Wittgenstein, George Lakoff/Mark Johnson, Thomas Jefferson, Germaine Greer, and Riane Eisler, and two essays examine further the contributions of Duchamp and Mallarmé.