I know I am not the only one to have been confused between these words. I love writing, but grammar has not always gotten me very excited. It’s like running for fun (writing) but not wanting to exercise (Grammar). While I’ve always excelled in English, this is one confusing language! It’s the only one where a maybe, possibly, perhaps, and I’ll try exists. Everyone else just says yes or no! In any event, we must know these things as writers because our English teachers said so. Sooo, below is an excellent breakdown I found online on the difference between Lay, Lie, Laid, and Lain by Brian A. Klems:
Lay
Lay and lie are both present-tense verbs, but they don’t mean quite the same thing. Lay means to put or set something down, so if the subject is acting on an object, it’s “lay.” For example, I lay down the book. You, the subject, set down the book, the object.
Lie
Lie, on the other hand, is defined as, “to be, to stay or to assume rest in a horizontal position,” so the subject is the one doing the lying—I lie down to sleep or When I pick up a copy of my favorite magazine, Writer’s Digest, I lie down to take in all its great information—and not acting on an object. In both these cases, you, the subject, are setting yourself down. Are you with me so far?
I Lie Down vs. Now I Lay Me Down (to Sleep)
To clarify things further, I’ll answer this question that you’re probably wondering: How can you be lying down in your examples while the classic nighttime prayer for kids clearly begins “Now I lay me down to sleep”? You must be out of your mind! It’s true, I’m totally out of my mind, but both the examples I used and the kids’ prayer are correct—and here’s why.
In I lie down to sleep, there is no object to the sentence, just subject (I). In Now I lay me down to sleep, there is a subject (I) and an object (me). Even though the subject and object are one and the same, the object is still present in the sentence, so you must use lay.
Laid vs. Lay vs. Lain
In the past tense, “lay” becomes “laid” (Last week I laid down the law and told her it was inappropriate for her to pick her nose) and “lie” becomes “lay” (Yesterday she lay down for a nap that afternoon and picked her nose anyway). Yes, “lay” is also the past tense of “lie.” And the confusion doesn’t end there.
To throw you for another loop, “laid” is also the past participle form of “lay.” So, when helping verbs are involved, “lay” becomes “laid” and “lie” becomes “lain.” Grandma had laid the chicken in the oven earlier this morning. The chicken had lain there all day until it was cooked all the way through and ready for us to eat.
Remember: Lay and laid both mean to set something down, while lie, lay and lain all mean the subject is setting itself down.
And now, I lay this question to rest. (Enjoy this totally awesome chart below to help you keep track of when to use lay, lie, laid, lain and more.
Lay vs. Lie Chart
Infinitive Definition Present Past Past Participle Present Participle
to lay to put or place lay(s) laid laid laying
something down
to lie to rest or recline lie(s) lay lain lying
The PBS Blog 