And there are also many other things which Jesus did, the which, if they should be written every one, I suppose that even the world itself could not contain the books that should be written. Amen.I find it charming that he sums up the record using the name of his friend, instead of one of Jesus' many titles in His role as Savior of the world.
We get John's point - there's lots that the Savior did and said during his life that wasn't recorded, or was recorded and then lost. This raises an interesting question - if further works or teachings of Jesus Christ came to light, should they not be studied and pondered and applied to our lives?
I should think so, enthusiastically. Though there's the challenge of identifying what might have come from the Savior.
In 1945 a work called The Gospel of Thomas was discovered in Egypt. It purported to contain many statements made by the Savior during his lifetime. The claim is substantively true, for many of the 114 sayings match Biblical sayings very closely.
There are many that aren't in the Bible, however. This parable, teaching 97, is fascinating:
Jesus said: The kingdom of the [Father] is like a woman carrying a jar full of meal. While she was walking [on a] distant road, the handle of the jar broke (and) the meal poured out behind her on the road. She was unaware, she had not noticed the misfortune. When she came to her house, she put the jar down (and) found it empty.Blatz's translation. Original and translation found here.
I haven't done enough to know whether this is true or not, but I like it a lot. It feels like something the Savior would have said. I don't know that I can make a stronger statement than that about it. Very close in style to the parables we are familiar with in the New Testament. The wide range of applications is significant, too - a people carrying along a heritage, or the results an individual expects from their labors. Awareness of surroundings, attention to important details, the consequence of slow and steady losses, and a key irony that turns productive labor into useless toil. It also has conflicts and details that promote further thought - for example, how could the lady not know her jar was empty?
My LDS religious tradition has encouraged open-minded study of non-canonical teachings, the Apocrypha in particular. Doctrine and Covenants 131:
Verily, thus saith the Lord unto you concerning the Apocrypha—There are many things contained therein that are true, and it is mostly translated correctly;
Therefore, whoso readeth it, let him understand, for the Spirit manifesteth truth;
And whoso is enlightened by the Spirit shall obtain benefit therefrom;
While I believe the LDS people to be more studious than the average, not many Latter-day Saints avail themselves of this particular opportunity, myself included. Missed opportunities.