The author discusses the different phases of cancer research from a rather philosophical watch tower. The details of the elaborate discussions are not suitable for review. The general scope is best indicated in the author's own words: "For the most part the proposed explanatory theories are mere paraphrases of existing obvious conditions. Others are theoretical speculations, visionary hypotheses or rather guesses, unsupported by concrete facts. Imagination has been given free scope; regard to facts has given way to arbitrary autochthonous ideas, of which there has apparently been no dearth."