Written when quantum mechanics was in its infancy, this book was among the first to recognize the incompatibility of Einstein's relativity with quantum theory. Although it proposes no solution, it clearly identifies the problems and suggests avenues for research, and does outline Whyte's newly-formed Unitary Course Theory. The book is divided into three major sections:

- Space-Time
- Coordinate Theories from the Standpoint of Unitary Course Theory
- General Features of Unitary Course Theory

Whyte argues that a universal length is necessary for any theory of the structure of matter, but recognizes four such lengths: the Rydberg wavelength, the de Broglie or Compton wavelength for the electron and proton, and a fourth wavelength differing by a factor of the fine structure constant. A unitary theory, he continues, must reduce the four independent universla lengths to one; alternately such a theory must explain the three dimensionless constants: (1) fine-structure, (2) proton to electron mass, and (3) e^{2}/GM^{2}.