Tim Daly on literate programming: we write down code which is what we do, but we didn't write down why and this why is super important.
Consider the action of "go to school". It is getting the bag, puting on shoes, getting out of the doors, and walking toward the location called school. If we drescibe it action by action, later when we read it it will be a puzzle on what we are doing -- we are missing th e why. So consider following code:
$call go_to_school
subcode: go_to_school
$call get_bag
$call put_on_shoes
$call get_out_of_door
$call wark_toward, school
subcode: get_bag
...
So literate programming is not documentaion + code. It is only when the programming language used for code is primitive and doesn't allow for properl writing, one needs add literate documentaion to explain why, and the result is often overly verbosity, and reviewers stil l need read the code. Even we know someone is "going to school", watching them actually walking the path can still be puzzling.
With proper facility in programming langauge, we can write code directly in literate way.