The history of optical design has engendered theoretical work originating in different countries, and using different nomenclature and sign conventions. Michael Kidger was adept at selecting topics that would be useful in the mainstream of optical design, reducing theory to the essentials and rewriting it using a common nomenclature and sign convention. This work, published after Kidger's death with the help of his colleagues, provides all the essential and best elements of his courses taught worldwide on lens and optical design.