[001] by the charter drawn on the making of a gift: if the charter alone is denied, that does [002] not suffice, unless the gift is also denied; where one says I deny the charter, he fails [003] to say enough. If he says I deny the gift and the charter, the tenant must then prove [004] both. If he says only I deny the gift, that is still sufficient, because a gift may be [005] good and complete even without a charter, and a charter may well be genuine, but, [006] in the absence of a completed gift, empty and without effect, [If the gift is good and [007] complete, each may be strengthened by the other.] and thus the gift may be good [008] though the charter is false, and the charter good though the gift is invalid or imperfect, [009] as where a donee intrudes himself on his own authority and without a warrant. [010] Thus it is not enough to prove the charter genuine unless the gift is proved valid and [011] complete.1 When the instrument and agreement are proved and it is necessary to [012] proceed further, they either know positively that it was satisfied or was not satisfied, [013] and accordingly, the matter will be determined for one party or the other. If they [014] know nothing whatever of any agreement, the plaintiff will recover, the exception [015] being, so to speak, void. If they are in doubt as to whether the agreement was satisfied [016] or not, though they know that an agreement was made, if they raise probable presumptions [017] for one party or the other, the presumption must stand, in view of the [018] doubt, since neither party has real proof by which it may be overcome. A presumption [019] may be strengthened subsequently, [as] where it is in favour of him who acknowledges [020] the agreement, but in his replication says that it was remitted. If there is a presumption [021] in his favour, it may be strengthened by an instrument subsequently found on [022] this side which shows the truth. If the tenant has no document whatever, he must [023] then prove the exception of agreement in another way. He then either puts himself [024] on the assise to be taken in the manner of a jury or does not. If he wishes to prove it [025] by his own servants or members of his household, that is not permitted. If by the [026] servants and household members of the other party, that is not likely to be successful. [027] If jointly by both, they will never agree. He must therefore of necessity have recourse [028] to the assise, joining to it any who were present at the making of the agreement, [029] provided they are connected with neither party. If he has no document and does not [030] wish to put himself on the jury, but has suit, one or several, whether they are members [031] of his household or not, by force of that he has at least a presumption in his favor, [032] which must stand until the contrary is proved. The contrary may be proved by wager [033] of law, for law overcomes suit.2 Suppose that one who has