"Lay" vs "lie" - When to use each?

Question

Which is correct in the following? I can never remember!

* She went to lay/lie down for a nap.

* Lay/Lie that book down on the table.

Answer 1

"lay" refers to objects "lay down the book"

"lie" refers to people "lie down and relax"

Answer 2

She went to lie down for a nap.

Lay that book down on the table.

You "lay" an object down but you "lie" down.

Answer 3

LAY/LIE

You lay down the book you’ve been reading, but you lie down when you go to bed. In the present tense, if the subject is acting on some other object, it’s “lay.” If the subject is lying down, then it’s “lie.” This distinction is often not made in informal speech, partly because in the past tense the words sound much more alike: “He lay down for a nap,” but “He laid down the law.” If the subject is already at rest, you might “let it lie.” If a helping verb is involved, you need the past participle forms. “Lie” becomes “lain” and “lay” becomes “laid”: “He had just lain down for a nap,” and “His daughter had laid the gerbil on his nose.”

Answer 4

1. She went to lie down for a nap

2. Lay that book down the table.

LAY- to beat or strike down with force 2 a: to put or set down <lay your books on the table> b: to place for rest or sleep;

LIE- to be or to stay at rest in a horizontal position : be prostrate : rest, recline <lie motionless> <lie asleep> b: to assume a horizontal position  

Answer 5

She went to lie down for a nap.

Lay that book down on the table.

Also:

She lay down to sleep last night at 1a.m.

The hen will soon lay an egg.

The hen laid about five eggs last week.

Hope these examples give you a good idea now on the usage.