12 As has been already observed, trusts in their origin depended solely on the good faith of the heir, from which early history they derived both their name and their character: and it was for that reason that the Emperor Augustus made them legally binding obligations. And we, in our desire to surpass that prince, have recently made a constitution, suggested by a matter brought before us by the eminent Tribonian, quaestor of our sacred palace, by which it is enacted, that if a testator charges his heir with a trust to transfer the whole inheritance or some specific thing, and the trust cannot be proved by writing or by the evidence of five witnesses--five being, as is known, the number required by law for the proof of oral trusts--through there having been fewer witnesses than five, or even none at all, and if the heir, whether it be his own son or some one else whom the testator has chosen to trust, and by whom he desired the transfer to be made, perfidiously refuses to execute the trust, and in fact denies that he was ever charged with it, the alleged beneficiary, having previously sworn to his own good faith, may put the heir upon his oath: whereupon the heir may be compelled to swear that no trust was ever charged upon him, or, in default, to transfer the inheritance or the specific thing, as the case may be, in order that the last wishes of the testator, the fulfilment of which he has left to the honour of his heir, may not be defeated. We have also prescribed the same procedure where the person charged with a trust is a legatee or already himself a transferee under a prior trust. Finally, if the person charged admits the trust, but tries to shelter himself behind legal technicalities, he may most certainly be compelled to perform his obligation. TITLE XXIV. OF TRUST BEQUESTS OF SINGLE THINGS Single things can be left in trust as well as inheritances; land, for instance, slaves, clothing, gold, silver, and coined money; and the trust may be imposed either on an heir or on a legatee, although a legatee cannot be charged with a legacy. 1 Not only the testator's property, but that of an heir, or legatee, or person already benefited by a trust, or any one else may be given by a trust. Thus a legatee, or a person in whose favour the testator has already created a trust, may be asked to transfer either a thing left to him, or any other thing belonging to himself or a stranger, provided always that he is not charged with a trust to transfer more than he takes by the will, for in respect of such excess the trust would be void. When a person is charged by a trust to transfer a thing belonging to some one else, he must either purchase and deliver it, or pay its value.