Since Don T. commented thoughtfully about my post on the line from "A Sailor's Prayer"

    "I will not lie me down, this rain a-ragin' ",

I'd like to explain how I see the rules for lie and lay, because using these verbs give everyone a lot of trouble, in general. They're highly irregular verbs, and it's additionally confusing that lie even has lay as a past tense.

The commonest confusion involves the meanings to lie, "to rest in a horizontal position" and to lay, "to place something down".

Lay is a transitive verb, so there must be a something to place or put down. "They lay the carpet in the room." (They lay what? They lay the carpet.) The past tense of lay is laid: "Yesterday they laid the carpet."

Lie is intransitive, and never has an object. "We lie in the sun." ("We lie what?" doesn't make sense here.) The past tense of lie is lay, confusingly: "Yesterday we lay in the sun."

So, "Now I lay me down to sleep" is standard usage, and "I will not lie me down" is not. Richard Lederer once said he used the warning mnemonic, "You only lay down when you have carnal relations with a duck!"

In the chorus line from the song "A Sailor's Prayer", I read into it that the sailor well knows the coarse meaning of "to lay", and he wants to present himself as seriously making a solemn vow, not as Barnacle Bill. That, to me, is what makes his mistaken grammar poignant.

[PS: I consulted and took examples from William F. Russell's book The Parents' Handbook of Grammar and Usage (1982, Stein and Day, New York).]