Ah yes, the lie versus lay debacle. And Eric Clapton got it wrong. Admittedly, this is a pet peeve of mine -- especially when I see the mistake in New York Times bestsellers. I had a critique partner once who stopped using lie and lay in her writing because she wasn't sure of the difference and didn't want me yelling at her for using them wrong. Of course, I never yell... :)
BE NOT AFRAID. The whole lie/lay thing is very simple once you do two things: 1. Learn the difference between a transitive and intransitive verb, and 2. Memorize the past tense and past participle of each verb.
Here we go:
A transitive verb is one that requires a direct object. To lay is a transitive verb. You lay something on the table, but you don't lay down. You can lay another person down (physically, you're laying him on the bed) but you yourself cannot lay down, nor can you tell another person to lay down. Yes, I'm sorry, but Eric Clapton is grammatically incorrect when he commands Sally to lay down.
To the contrary, an intransitive verb is a verb that has no object. To lie is such a verb. To die and to sleep are other examples of intransitive verbs. You can't sleep someone, or die someone or something. You and you alone can only sleep or die yourself. You also can't lie something. You can only lie down yourself.
Repeat after me: To lay is transitive. To lie is intransitive.
Now that you know which verb to use, let's look at their forms. This gets sticky for some people because they've said it wrong for so long, the correct form doesn't sound right to them. Trust me, you'll get used to it.
Broken down, here are the forms:
present tense -- lay
past tense -- laid
past participle -- laid
present tense -- lie
past tense -- lay
past participle -- lain (this is the one that seems to freak people out)
Let's put them into action:
Today I lie down. Yesterday I lay down. For the past three weeks, I have lain down for a nap each afternoon.
Today I lay the pencil on the table. Yesterday I laid the pencil on the table. For the past three weeks, I have laid a pencil on the table every afternoon.
Simple, yes? I hope this clears up the mystery of lay vs. lie.