These verbs cause trouble for many people. If you mean repose
, use lie.
If you mean set
, use lay.
An easy way to remember which one to use is to recognize that lie does not take an object and lay does:
I lie down for a nap everyday.
The dog lies by the fire.
I lay the paper on the table.
I lay myself down (here myself becomes the object)
The past tense and the past participles of lie are lay and lain:
I lay down for a nap yesterday.
I have lain down every afternoon this week.
The past tense and the past participles of lay are laid and laid:
I laid the paper on the table yesterday.
I have laid it in the same spot for years.