They know what bringing out boxes and luggage means well enough.
Sam knew, I am sure; but he did not care for us.

He was only uneasy because he thought Harper was going, and he should lose his shooting; and as soon as he saw Harper was not getting into the boat, he sat down and scratched himself, quite happy.

But do dogs think?
Of course they do, only they do not think in words, as we do.
But how can they think without words?
That is very difficult for you and me to imagine, because we always think in words.

They must think in pictures, I suppose, by remembering things which have happened to them.

You and I do that in our dreams.