Explore the second lecture in a series on Metamaterials and Topological Mechanics, delivered by Tom Lubensky from the University of Pennsylvania. Delve into classical elasticity, examining concepts such as pure deformations, free energy, isotropic materials, and Lame coefficients. Investigate examples including uniaxial crystals and the Voigt-Kelvin model. Analyze forces and stresses in elastic materials, and participate in a Q&A session. This 88-minute lecture, part of the Infosys-ICTS Chandrasekhar Lectures series, provides an in-depth exploration of the fundamental principles underlying topological mechanical materials and their unique properties.