His going forth is from the end of the heaven and his circuit unto the ends of it: and there is nothing hid from the heat thereof. Psalms 19:6, KJV

It is comforting to know the sun will rise and set like usual.  It is predictable and mankind can make plans.     

The circuits and returns are awe inspiring to men.  A person has trouble putting it into words.  The psalmist described creation as having a voice and speech that can be heard around the world.  

Part of the circuit is that it returns where it came from. In modern times, returns have a bad connotation like  returning a defective item to the store.  But the return can be good or bad: wishing someone "many happy returns" or the letter is returned because of a wrong address.
                                                                   

A circuit  and its return is simply a path, like brushing teeth.  You brush your teeth before going to bed.  And you return to do it again the next morning and the next. 

 A growing Christian will create a circuit and return by reading the Bible in the morning, and praying at the end of the day.  This time is needed for renewing the inward man. (2 Cor. 4:16, KJV) and prepares him for the day:  maybe a requested verse to comfort someone who lost a husband., receive strength and patience to deal with children or elderly parents, or wisdom to make wise decisions. You aren't going to have these if you don't take time to complete the circuit and return between God and man.