Аннотация: This book provides insights into the tight connection between fundamental math and mechanics, the basic grounding of physics. It demonstrates that quantum, classical, and relativistic mechanics, historically (and separately) formulated upon an experimental basis, can be regarded as links of a single theoretical chain readily extracted from a simple mathematical medium. It uses mathematical tools to endow formerly abstract entities, such as quantum wave-function and classical action function, with original and clear geometric images, strongly simplifying them. The book comprises the author’s lectures, manual texts, typical problems and tests, and many illustrations, and will be of interest to students of all levels majoring in mathematics, physics and advanced engineering programs.