Textbook in PDF format These two volumes cover the classical topics typically taught in undergraduate physics courses and beyond. However, we teach classical physics using a very different language from traditional books, influenced by the language of modern physics, in a move to encourage a positive approach towards the latter subject. Based around the unifying concept of energy, we take a distinct approach to the organisation of material, presenting physics in a cohesive manner without separating topics such as mechanics, kinematics, thermodynamics, electricity, and magnetism. Instead, physics is revealed gradually, emphasising a holistic approach to science. Despite this peculiarity, we have maintained the conventional separation between Physics I and II to assist teachers in smoothly integrating these books into their courses. These innovative volumes present valuable new perspectives. Although their approach is bold, they will certainly prompt interesting reflections on traditional teachings. This first volume contains chapters on temperature, optics, waves, motion, special relativity, Newton's laws, forces and work, inertial and non-inertial frames, momentum, the physics of gases, and thermodynamics, among other topics