form and shadow; inseparable things
A classical literary expression for two things that are as inseparable as an object and its shadow. Not used in everyday speech; appears in old texts or poetic language.
There is a phrase 'form and shadow go together,' meaning two things are inseparable.
inseparable as form and shadow; deeds reflecting the mind; husband and wife never apart
A compound of 形 (form, shape) and 影 (shadow), literally 'form and shadow,' used metaphorically for inseparable things. The exact historical derivation is uncertain; it is a classical Chinese-derived expression.