One more preliminary distinction must be made. A trustee can make a contract for the benefit of his cestui que trust, and if the contract is not performed may sue and recover full damages. A contract by which A engages to pay B money as trustee for C is unquestionably valid.24 And if B refuses to enforce the contract, C may bring a bill in equity against A and B, the primary equity of which is to compel the trustee to do his duty, but to avoid multiplicity of actions a court of equity will decree that A pay the money.25 It is only in case the trustee, who is the promisee, refuses to act, that the beneficiary has a right to sue in this way.26