20.Agreement void where both parties are under mistake as to matter of fact

Where^ⓘ both^ⓘ the parties^ⓘ to an agreement^ⓘ are under^ⓘ a mistake^ⓘ as to a matter^ⓘ of fact^ⓘ essential to the agreement^ⓘ, the agreement^ⓘ is void^ⓘ. Explanation.--An erroneous opinion as to the value of the thing which forms the subject-matter^ⓘ of the agreement^ⓘ, is not to be deemed a mistake^ⓘ as to a matter^ⓘ of fact^ⓘ. Illustrations (a) A agrees to sell to B a specific cargo of goods supposed to be on its way from England to Bombay. It turns out that, before the day of the bargain, the ship conveying the cargo had been cast away and the goods lost. Neither party was aware of the these fact^ⓘs. The agreement^ⓘ is void^ⓘ. (b) A agrees to buy from B a certain horse. It turns out that the horse was dead at the time of the bargain, though neither party was aware of the fact^ⓘ. The agreement^ⓘ is void^ⓘ. (c) A, being entitled to an estate for the life of B, agrees to sell it to C. B was dead at the time of the agreement^ⓘ, but both^ⓘ parties^ⓘ were ignorant of the fact^ⓘ. The agreement^ⓘ is void^ⓘ.