(Latin: "I give, that you may give")

In Roman law, a principle stating that a party to a contract is only bound to uphold his part of the contract, if the other party upholds his.

In religious phenomenology, this concept is reflected in the act of sacrifice (sacrificium): one makes sacrifice to the deity to sustain the deity, in return expecting to receive aid from the deity. This basic view of the relationship between deity and worshipper is widespread.