This book discusses in detail the concept of light quanta (photons) and presents a historical survey of the ideas involved. It analyses critically the principles of complementarity and correspondence as well as the quantization procedure. The work of Wigner, Newton and Wightman on localized states is discussed. The author presents many new ideas and gives a new way of defining the position operator. He invites physicists to look in new directions and aims to convince the reader that light quanta are not compatible with our present concept of space in quantum physics. The book should be of interest to students as well as to researchers in modern physics and should revive the discussion of the foundations of modern physics.