Contracts in this respect are divided into real, verbal, literal, and consensual. The Roman system prescribed certain forms as essential to the validity of contracts, on the same principle as is adopted by our statute of frauds in reference to certain classes of contracts. But outside of these forms there were two other modes by which parties could bind themselves. These were by performance on one side, and by a privilege attached to certain single specified contracts which were valid without form. The reasons given for requiring specific forms to be adopted were the dangers of fraud, and the necessity of precision in a transaction by which the will of one person is subjected to the will of another person. These forms were of two kinds-oral and written-verba, literœ,; verborum, literarum obligatio. Of oral contracts there were two kinds: nexus and stipulation. Real contracts (re contracta obligatio) were contracts which were not embraced within either of the classes above mentioned, but which had been performed on the one side. The special contracts, which were privileged without form (consensu contracta obligatio, consensual contract), were four: emtio venditio, locatio con-ductio, societas, and mandatum. The reason was that contracts of sales and of service were so numerous, and related often to transactions so trivial, that it would be inconvenient and oppressive to require them to be executed in the form of the stipulation. Societas and mandat were excepted as being virtually real contracts, not existing until there was on one side or the other something in the way of part performance.

The normal form was the oral, and in the old law took the name of nexus (Koch, 2, p. 61). Five witnesses and a libripens were essential to perfect the transaction, which symbolized a weighing of gold and then a loan of the gold weighed. The creditor then asked the debtor whether he had received the gold, to which question the debtor replied, acknowledging the receipt and the debt. Of later introduction was the stipulation, in which there were no scales or specified attesting witnesses. The essence of the stipulation was that when the parties met, the one (the stipulator) should ask whether the other agreed, upon which the other (the promisor) answered. No fixed words were prescribed ; the only requisite was that the answer should apply exactly to the question. The form " spondes " " spondeo," however, which in prior times was essential to the nexus, was always regarded as valid when used in the stipulation. But no form of words consideration of the promise of the other, the one is not bound unless the other is bound.1 A promise to do a thing on an executed consideration is not a contract;2 nor is a promise to do a thing in consideration of an illegal or impossible engagement on the other side.3 "Without this reciprocal obligation, no contract can be constituted.4 "It is a general principle," says Mr. Fry, "that when, from personal incapacity, the nature of the contract, or any other cause, a contract is incapable of being enforced against one party, that party is equally incapable of enforcing it specifically against the other, though its execution in the latter way might in itself be free from difficulty attending its execution in the former."5 It is said, indeed, that this rule is subject to certain important exceptions, prominent among which, it is alleged, is that of an infant, a party contracting with an infant being bound to the infant, but the infant not being bound to such other contracting party.6 But this is a mistake. An infant, it is now generally agreed, is bound by his contracts, though they cannot be enforced against him until he is of full age, was requisite to the validity of the stipulation. All that was required was that there should be a concurrence as to the thing. For a long time the personal presence of the parties was essential. When writing subsequently became a common mode of business, it was held that when a written agreement existed it would be presumed that the forms of the stipulation had been adopted.

It will be seen, therefore, that by the Roman law the great body of contracts (embracing sales and most bailments) required no special form ; that special oral contracts, indeed, had to be put in the form of stipulations ; but that written special contracts were at least prima facie valid.

1 Infra, sec 523. 2 Infra, sec 514. 3 Infra, sec 509 et seq. 4 Kennawayr. Treleavan, 5 M. & W. 498 ; Arnold v. Poole, 4 M. & G. 860;.

Lees v. Whitcomb, 5 Bing. 34; Head v. Diggon, 3 Man. & R. 97 ; Martin v. Mitchell, 2 Jac. & W. 413 ; Jenness v. Iron Co., 53 Me. 20; Dresel v. Jordan, 104 Mass. 412; Keep v. Goodrich, 12 Johns. 397 ; Tucker v. Woods, 12 Johns. 190. In Cooke v. Oxley, 3 T. R. 653, Lord Kenyon said "the other party was not bound: it. was therefore nudum pactum." That in promises to marry mutuality is essential, see Daniel v. Bowles, 2 C. & P. 553; Wightman v. Coates, 15 Mass. 5 ; Russell v. Cowles, 15 Gray, 582 ; Waters v. Bristol, 26 Conn. 398 ; Southard v. Rexford, 6 Cow. 254; Moritz v. Melhorn, 13 Penn. St. 334; and other cases cited, 1 Ch. on Con. 11th ed. 22.

5 Spec. Per. sec 286 ; adopted in Stnr-gis v. Galindo, Sup. Ct. Cal. 1881, 13 Rep. 266.

6 1 Ch. on Cont. 11th Am. ed. 23.

and although when he arrives at full age they may be repudiated by him.1 But this is part of the limitation of the contract itself. The contract is binding on him on a contingency, i. e., its non-repudiation at a specified period; and it stands on the same footing, therefore, as sales on trial,and other conditional contracts.2 It is the very essence, as will be hereafter seen, of a conditional promise that it is limited on an uncertainty ;3 and here the uncertainty is non-repudiation at majority. It is also said that exceptions to the rule requiring mutuality are to be found in cases where one of the parties is defrauded, in cases where one of the parties can defend under the statute of frauds, and in cases where an agent turns out to be acting fora principal subsequentlydisclosed. But in all these cases the question of liability is raised by confession and avoidance; and if we are to hold that there is no contract in such cases, we must hold that there is no contract in any case in which one of the parties could interpose a good defence, no matter what that defence may be. In all these cases, also, the ratification (or non-repudiation, as it is more properly called)4 does not start a new contract; it merely confirms a contract already existing.5 In respect to contracts declared void on account of essential error, it may be said that the party who was under no mistake is bound, while the mistaken party is relieved. The answer to this, however, is, that the vacating as to one party vacates as to the other, as the consideration fails.6 The rule requiring mutuality is, not that the contract should bind in defiance of fraud, or of equities subsequently arising between the parties, but that each party should agree to perform his part. It may be that this part is to be performed only on a contingency. It may be that there is a failure of consideration, so that specific performance cannot be compelled.7 It may be that some insuperable obstacle may be afterwards interposed in the way of performance.8 But be this as it may, there must be mutuality when the contract is made, and this mutuality is essential to the making of the contract. A more difficult exception to deal with arises in cases of contracts with married women. A married woman may be incapable of contracting in a general sense of the term, and if she makes a contract for the purchase of real estate, that contract cannot be enforced against her, though if the contract be executed by her, it has been held that she may have a remedy against the other party.1 Now, in the first place, it does not follow that, because specific performance is refused in a particular line of cases, in such cases there is no contract. Specific performance is refused in many cases of contractual hardship in which a party can avail himself of the contractual relation in a court of law. And in the second place, a married woman, though technically unable to contract, may yet preclude herself by estoppel at least from fraudulently asserting title against a third party who is encouraged by her to buy a property to which she has a title, which she at the time knowingly suppresses.2 But, thirdly, and this is the best reason, after the married woman pays for and takes the property thus purchased by her, the vendor is himself estopped from denying her capacity. On the other hand, however, if we concede that she cannot be estopped, and that she has no contractual capacity whatever, then we must hold, in accordance with the great preponderance of authority, that there is no contract, and that where there is no contract the other party is not contractually bound. He may be bound for negligence, or for deceit, but he cannot be bound on a contract.3

1 Infra, sec 32.

2 Infra, sec 16, and see generally infra, sec 545.

3 Infra, sec 546.

4 See infra, sec 56 et seq.

5 See infra, sec 283-4. 6 Infra, sec 493 et seq. 7 Infra, sec 520. 8 Infra, sec 296 et seq.