The book "Vibrational Spectroscopy via Generalized Langevin Dynamics" by Fabian Gottwald offers a comprehensive investigation into the ability of the generalized Langevin equation (GLE) to simulate the dynamics of solute modes in liquid solvents. A detailed theoretical background is presented, illuminating the assumptions and models used as well as the numerical treatment. The investigation is conducted through linear absorption spectroscopy, with the central question being the applicability of the GLE formalism to the dynamics of solute modes in liquid solvents. The results show that only a linear form of the GLE yields correct spectra, while nonlinear GLEs, which preserve the anharmonicity of the system, exhibit fundamental mathematical problems. The book also outlines possible solutions for the explicit incorporation of the anharmonicity of the system potential into the formalism.