The text includes movement (ḥarakah) among qualities connected with perception. Movement can be understood as a gradual transition in place or state; its observable pattern may ground a likeness.
“A bird is like an arrow in speed of movement.”
“Flying leaves resemble moths in irregular motion.”
The shared aspect is a specific pattern of motion, not simply existence or colour. Speed, direction, continuity, or disorder may be the intended respect. Accurate analysis identifies which one the expression selects.