He took her by the hand. (the identity of 'the hand')

Question

He took her by the hand.

Whose is "the hand"? Could you tell me whose hand the hand is: his hand or her hand?

Answer 1

If one person seizes, grips, takes hold of, pulls, etc, part of a person, we can use 'by the' to discuss the relevant part of the other person.

The teacher took hold of the naughty boy by the ear and dragged him to the headmaster's study.

The kind man took the old lady by the arm and helped her across the road.

The dog seized me by the leg and would not let go.

The teacher led the child by the hand to the play area.

We can also use 'lead by the hand' figuratively to mean to guide someone in some task or situation as if they are a complete beginner or are helpless and unable to do it by themselves:

Joe said he was experienced with spreadsheets but I had to lead him by the hand to create a table!

On my first day at work I didn't know much about the work but Mary looked after me and led me by the hand until I was more confident.

When I met my husband he was very shy and I practically had to lead him by the hand to ask me for a date.

If someone 'leads you by the nose' they are controlling you completely and there is often a suggestion of deceit or exploitation of gullibility or lack of experience or knowledge:

I was led by the nose to invest in Bitcoin by someone I thought was a friend. Now I have lost all my money.

Answer 2

When part of somebody else's body is the direct object, the owner is usually expressed: She poked his arm, He kissed her hand.

But when the owner is already mentioned as the object, and the body-part is in a prepositional phrase, we don't usually specify the owner: She poked him in the arm, He kissed her on the forehead.

We can do so (He took her by her hand) but we don't usually.

So He took her by the hand is normal, and means her hand.

(In some languages, when the owner does something to their own body, the possessive is not used, but English usually does express the owner: eg I banged my head, He massaged his leg. Again, we don't use the possessive when we've already mentioned ourselves as the object: He hit himself on the nose.)

Answer 3

He took her by the hand
She slapped him round the head
He grabbed her about the waist
She took him by the throat
He took off by himself
She took herself home.

All of these are the first-mentioned does to the second-mentioned - even if in the last two instances, that is one and the same person.

Using his own hand, he held her hand. It's complete, but you really don't need all that information.

They held hands.
The overwhelming probability is that each held onto one hand of the other, not that they each held their own other hand, or the hands of random passing strangers.