As per Sec 36 of ICA 1872, Agreements contingent on impossible event void.—Contingent agreements to do or not to do anything, if an impossible event happens, are void, whether the impossibility of the event is known or not to the parties to the agreement at the time when it is made. —Contingent agreements to do or not to do anything, if an impossible event happens, are void, whether the impossibility of the event is known or not to the parties to the agreement at the time when it is made.
Though it is a matter of void ab initio, but it has to be stated under a definite law, mere general understanding of principles does not bound the people to follow it. Its compliance with the law is an integral part for people to be bound through it, hence Sec 36 is stated specifically under the Contingent Agreement.