The classification investigates the two terms of comparison by considering the manner in which they are apprehended. Three principles follow.
First: sensory includes all five external senses, not merely vision.
Second: a sensory term and an intellectual term can be compared when a relevant shared respect is intended; their complete natures need not coincide.
Third: khayālī, wahmī, and wijdānī cases show that the mind can combine sensed forms and experience inward states beyond direct observation.
A sound rhetorical analysis identifies which two things are compared, in what cognitive capacity, and through what shared feature.