“Hand-in-Waistcoat”
In the 1995 essay by Arline Meyer, we can find an explanation for the appeal of the famous “hidden hand” pose in the 1800s.
The essay, titled “Re-dressing Classical Statuary: The Eighteenth-Century “Hand-in-Waistcoat” Portrait,” described the pose as a way to indicate that a portrait’s subject was of “good humor and suitably elevated in character.”