It is known in the world that there are many reasons for coldness in marriage, and that these are due to many outward causes. But it is not generally known that the sources of these lie hidden at the inmost level, and spread to the following levels, until they become apparent outwardly. To ensure therefore that it is known that the outward causes are not in themselves the basic reasons, but are derived from these, which, as I said, are at the inmost levels, I begin by classifying the causes generally as inward and outward, and then proceed to their detailed investigation.