The whole video here by NT Wright is worth watching.

He so reminds me of C.S. Lewis with his series of apt metaphors. Here are three

Think if I offered you a drivers license, claiming i had authority to issue it
-Think if someone destroyed all bank records and evidence of any debt you owe?
Think what would happen if you pointed at something, hoping for your dog to look at it?

But let's focus on the third (4:13ff) here:

The telling and true-to-life illustration of pointing your dog towards something;
and the temple being a signpost pointing to something (Someone) else is so good.

Try it on your dog, I double dog dare you(:

He may have clarified this in the longer video of which this is an excerpt, but it's likely Wright is actually drawing (as he often acknowledges) on C.S. Lewis:

The sunlight in a picture is therefore not related to real sunlight simply as written words are to spoken. It is a sign but something more than a sign, because in it the thing signified is really in a certain mode present. If I had to name the relation I should call it not symbolical but sacramental..
..I have tried to stress throughout the inevitableness of the error made about every transposition by one who approaches it from the lower medium only..You will have noticed that most dogs cannot understand pointing. You point to a bit of food on the floor; the dog, instead of looking at the floor, sniffs at your finger. A finger is a finger to him, and that is all. -"Transposition," from The Weight of Glory...someone has uploaded the whole essay here)

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