God remains a mystery even after he has revealed his nature through his only Son. The limited human mind can never grasp fully the mystery of God, because only GOD THE INFINITE, THE ETERNAL, can understand Himself completely.

A story is told that St. Augustine of Hippo one day was waking along the seashore determined to solve the mystery of the Trinity.

As he was walking along he saw a child taking sea water and pouring it into a hole in the sand. He stopped and asked the child what he was doing. The child explained that he was putting all the water of the sea into the hole. St. Augustine exclaimed, but that is impossible.

The child (presumably an angel) told the Saint, so is your effort to solve the mystery of the Trinity impossible.