Expression, in the context of sign language, refers to the essential body postures and facial expressions that accompany gestures, forming a vital component of signed communication alongside handshape, orientation, and movement. This concept extends beyond linguistics, as authors like Henry Fuseli described it as the "vivid image of the passion" shaping human features and gestures, while John Ruskin emphasized the importance of "dignity and simplicity of manner" in intellectual growth.
Alfred North Whitehead connected expression to life’s complexity, encompassing desire and emotion, and William Mathews highlighted its role in guiding thought and will through language. Synthesizing these perspectives, expression emerges as a bridge between internal experience and external articulation, shaping both linguistic form and human understanding.