A question may arise, why Manamayakosh should be the mother, and Anandamayakosh and Vignanamayakosh should be the daughters. And the answer is that they are born of mind, born of mind and soul. If there were only the soul there would be neither joy nor wisdom. Mind and soul both produce joy and wisdom. Therefore the latter are the daughters, because mind is the mother. The two lower planes are represented by the sons-in-law because they were not directly born of mind and soul; it was a separate substance mind and soul have taken into their life.