“Lies with his daughter in law” means the incorrect connection between the lower and the higher level of the spiritual system.
The lower level can directly contact only with a father and a mother because it has a common direct connection with them. All other communications are considered secondary.
If the lower degree comes into a wrong contact with a higher degree, it results in a short circuit. The lower degree can receive light from the higher degree, only through certain filters, the so-called gradation Tselem (Tzadik, Lamed, Mem), i.e., the image and likeness. As it is written, “By His own image I created a man.”
The spiritual system is designed so that the Creator comes first, second is His image and likeness, and then the degree of a man. Therefore, the image and likeness are filters, the system of gradual reduction of an impact towards a person to the point where one becomes something similar to the Creator but still remains at a lower level than the Creator.
This is a light attenuation system of filters, which are divided into many categories, such as, the quality of light, its amount on the left and right lines, etc. While explaining this system, Baal HaSulam gives an example of a person who can look at the sun only through special sunglasses.
From KabTV’s “Secrets of the Eternal Book” 4/23/14