One of the Wordy Bird’s biggest pet peeves is misuse of the words lay and lie, and it's also probably the most common grammar mistake I see.
Nestmate pointed at Baxter. “Lay down,” he said. Baxter laid down. Nestmate laid down beside the dog. Chickling laid on top of them.
What’s wrong with this?
“It’s lie down!” puffed Wordy Bird. “Not lay down. Unless you are actually laying the dog down, which you’re not.”
Lay is a transitive verb, so Baxter cannot lay down—
Ok, let’s back up a bit. What’s a transitive verb? A transitive verb takes an object. For example: put. You wouldn’t say:
The dog put.
It doesn’t make sense, does it? A transitive verb must take an object for the sentence to make sense.
The dog put the bone down.
The opposite of a transitive verb is an intransitive verb, for example: run.
The dog runs.
An intransitive verb doesn’t take an object.
Lie is an intransitive verb, so it doesn’t take an object. Some of the confusion between the two verbs comes from similarities when they are inflected:
Lie, lay, lain
Baxter lies down. Baxter lay down. Baxter has lain down.
But the transitive verb lay is inflected like this: lay, laid, laid
Baxter lays the bone down. Baxter laid the bone down. Baxter has laid the bone down.
So when Nestmate wants the dog to be on the floor, he should say:
“Lie down, Baxter. Good boy.”
Then he can lie beside the dog and Chickling will lay herself over both of them and everyone will be happy. Especially Wordy Bird.