Of all the Apostles, Paul was the most educated. Being a Pharisee, and trained to become a rabbi, he had the equivalent of a college education in the Judaic religion of his day.
He was appointed by Christ to be the Apostle to the Gentile nations, primarily the Greeks and Romans, for a reason. The Greeks and Romans , and Ephesus was a Greek city, were big on ‘logic and reason’ in their daily lives, and so were having a few difficulties with accepting the tenets new Christian religion.
In this passage, he is explaining to them that faith is the key to the kingdom and that key is love itself.
3:17:
17 That Christ may dwell in your hearts by faith; that ye, being rooted and grounded in love,
I doubt that Paul was referring to any higher order of things in the universe, he was just trying to make things as simple as possible to a people who depended on facts and hard evidence for their acceptance of ‘ the evidence of things not seen.’................
The referenced passage is in context a teaching on the supernatural experience Paul was blessed to have. Breadth, length, and height are understood today to reference three variables of dimension space. So why did Paul include ‘depth’ in his recitation of the variables of dimension space? I do not know, but it appears to indicate he had received a more-variables experience than we are able to have in our three of space and one of time coordinate system. Jesus had an extra variable reality, as evidenced by entering a six-sided room without opening a locked door or window. John indicates that we who are born again will have such an extra-variable reality when Christ appears to gather us unto Himself (1 John 3:2).