An estimative bond (الجامع الوهمي) arises when the mind groups two notions through a strongly perceived contrast or a related associative resemblance. The text discusses such pairings as black and white and faith and disbelief.
Some pairings are not strict logical contradictories; the point is that the listener’s association may operate beyond a precise shared essence. A vivid contrast can still organize the meaning.
For example, “One side felt hope, and the other fear” combines opposing experiences within one situation. Arbitrarily joining unrelated ideas, however, would not become rhetorical merely because the speaker labels the result an estimative bond.