This book provides an overview of theoretical physics in two levels. The first four chapters cover mechanics, electrodynamics, quantum mechanics, and statistical thermodynamics, focusing on conceptual foundations and unifying principles with a minimal amount of mathematical effort. The examples have been selected with the aim of promoting general scientific education and are presented in a way that requires only basic knowledge of calculus. The second part deepens the material and addresses more complex topics as well as research-relevant methods; the mathematical demands are higher, though still moderate. The theoretical foundations are provided for a number of now independent fields such as chemical thermodynamics, hydrodynamics, quantum field theory, etc. The book is aimed at students from various disciplines.