I think you need to read the entire book, Mrs. Tax, in order to appreciate how well he explains this.
True, the precis here is not much. However, he does the best explanation I have seen in the beginning of his book that our puny brains can handle. The Mystery of the Trinity is enough to ponder for Eternity (as St. Augustine was allegedly told by the small child attempting to empty the sea into a hole in the sand with a sea shell. Augustine laughed at him and the child told him that he would accomplish his task before Augustine understood the Trinity).
Oy. I’ll have to try the used-book listing on Amazon. But I hate paying postage!