Comparison
Unfamiliar matter may be made plain by showing how it resembles something already clearly understood by the audience. This is comparison. It shows how two things are alike. The old geographies used to state that the earth is an oblate spheroid, then explain that term by comparison with an orange, pointing out the essential flattening at the poles. In any use of comparison the resemblance must be real, not assumed. Many a speaker has been severely criticized for his facts because he asserted in comparison similarities that did not exist.