These lessons, chosen from the conferences given by Richard Feynman at the California Institute of Technology from 1961 to 1963, are a classical text that keeps being part of the essential bibliography to the current Physics students. This first volume is an introduction to Physics knowledge through these three fundamental axes: mechanics, radiation, and heat. It also addresses the subjects in a clearly manner from: what is the Physics subject of study and its connection with other sciences, Theory of Gravitation and the laws which govern the movement, energy concepts, work, force and momentum, to the study of optics and the general waves behavior.