Where the order in which reciprocal promises
are to be performed is expressly fixed by the contract, they shall be performed in that order; and where the
order is not expressly fixed by the contract, they shall be performed in that order which the nature of the
transaction requires.
Illustrations
(a) A and B contract that A shall build a house for B at a fixed price. A’s promise to build the house must be performed
before B’s promise to pay for it.
(b) A and B contract that A shall make over his stock-in-trade to B at a fixed price, and B promises to give security for the
payment of the money. A’s promise need not be performed until the security is given, for the nature of the transaction requires
that A should have security before he delivers up his stock.