BEICEELL, C. J.
Proceeding upon the general principle, that all persons materially interested, either legally or "beneficially, in the subject-matter of suit, must be made parties, either as plaintiffs or defendants, when, in a court of equity, the cause or subject of controversy is a legal chose in action which has been assigned, the assignor, if the legal title remains in him, or if the assignment is not absolute and unconditional, or if its extent or validity is disputed, must be made a party, that he may be bouud by the decree, and future litigation or a multiplicity of suits prevented. — 1 Dan. Ch. Pr. 198; Story’s Eq. PI. § 153. In any case, he is a proper party, because of his connection with the subject-matter of suit, and the privity of contract existing between him and the assignee, and the party bound by the chose in action. With his consent, he may be joined as a complainant with the assignee, or, at the election of the latter, made a party defendant. — Blevins v. Buck, 26 Ala. 292; 1 Dan. Ch. Pr. 200; Thompson v. McDonald, 2 Dev. & Bat. Eq. 476; Wilson v. Davidson, 3 Tenn. Ch. 546. If the assignment is not admitted, proof of it is material to maintain the right of the assignee to relief; and when the assignor is joined as a complainant, the admission of record obviates the necessity of making proof of the assignment, or of any of the facts or circumstances which may have attended it.
The assignment may pass to the assignee the entire beneficial interest, entitling him to all the relief which is prayed, or the court may grant. The rule is of general application, as is insisted by the counsel for the appellant Broughton, that if there be several complainants in a bill, some of whom have an interest, and are entitled to sue, while others are without an interest, or are barred of all right to relief, the misjoinder is fatal. The rule is not applied, when assignor and assignee join as complainants ; nor is it capable of application when, as in the present case, the legal title resides *221in the assignor, and there is a liability remaining on Mm, the decree may affect. — Thompson v. McDonald, supra. If Broughton is liable, on his contract with McCall, for the payment of the purchase-money, the decree rendered must be”in favor of the assignees, his co-complainants; none can be rendered in favor of McCall, because of the assignment by which the beneficial interest passed from him. This, however, diminishes no right of Broughton. A satisfaction of the decree discharges his contract, and extinguishes the legal title and the equitable interests the assignment created. Nor can it be of any consequence to Broughton, whether Mrs. Boyden and Mitchell share equally or unequally in the purchase-money, or that it is decreed to them jointly. It is-enough that he is fully discharged, and acquires the right and title of each of them, iu and to the lands. They may well be left upon their own terms to adjust their respective rights to the money.
2. We do not suppose the assignment of McCall to Mitchell and Mrs. Boyden is tainted with champerty, or maintenance. It is bona, fide, founded on a valuable consideration; and its validity is unaffected by the fact that the parties knew a suit would be necessary to fix the liability of Broughton. Independent, however, of that consideration, the assignment being admitted by assignor and assignee, and not depriving him of any defense, it was not for Broughton to inquire into its legality or illegality. — McCausland v. Drake, 3 Stew. 344; Oliver v. Jones, MSS.; Agee v. Medlock, 25 Ala. 281.
3. The contract between Broughton and McCall was made originally on the 5th day of November, 1860; and, as is recited in the writing, remained in parol until the 24th day of February, 1863, when the writing was executed. The writing is under seal, and is inartificially drawn; but an express recital, not qualified by any other recital or stipulation, is that the purchase-money of the lands was four thous- and nine hundred and fifty-one 95-100 dollars, due and payable on or before the first day of January, 1861. The wilting then recites, as its condition, that McCall and wife are to make Broughton a good and sufficient title to the lands, when they obtain title in pursuance of the contract entered into between McCall and Boyden and Mitchell. We concur with the counsel for Broughton, that, under the present bill, it is essential that the recovery should be on the contract made between Broughton and McCall, and not upon any independent right or equity which Mrs. Boyden and Mitchell could enforce against Broughton, or against the lands he purchased from McCall. The whole scope of the bill is, that Broughton *222was indebted to McCall, for the purchase-money of the lands, by a contract which was broken before and at the time of the filing of the bill, and that by assignment from McCall Mitchell and Mrs. Boyden had succeeded to McCall’s rights under the contract. The rights of Mrs. Boyden and Mitchell are identical with, no greater or less than, the rights of McCall.
If, by the terms of the contract, the making of the title to Broughton, and the payment by him of the purchase-money, were to be simultaneous, it must be admitted, that McCall could not maintain any suit at lawr, or in equity, upon the contract, unless he had performed, or was in readiness to perform, his part of the contract; and, according to some authorities, have given Broughton notice of his ability and readiness to perform, demanding performance from him. But is this the character of the contract into which the parties entered ? The inquiry must, be answered from the writing, and from that only, so far as it is clear and unambiguous in its terms : that is the sole expositor, the only criterion, of the intention of the parties. — 1 Chit. Con. 140-141. Eor more than a'year, these parties permitted this contract to remain in parol, and then deliberately reduced it to writing, joining in its execution, and calliug witnesses to attest it. No fraud, nor mistake, is imputed to either the one or the other, in the drawing or execution of the writing; and the conclusive legal presumption attaches, that all previous verbal stipulations are merged in the writing; or, if these are inconsistent with the writing, that they were intended to be superseded by the stipulations found in the writing. — 1 Brick. Dig. 865, §§ 866-870.
4. Whether performance by McCall of the contract on his part — the making of a good and sufficient title of the lands to Broughton — was a condition precedent to the right of the former to demand of the latter payment of the purchase-money ; or whether the making of title, and the payment of the purchase-money, were intended to be contemporaneous, is the important question of the case. The question depends on the meaning and intention of the parties, as expressed in the writing. A single instrument in writing may contain several, separate, independent covenants, promises, or agreements. The breach of one may furnish the party to whom it is made a cause of action against the promisor or covenantor, though there are covenants or promises he is bound to perform, and which he has not performed. This is true, whenever the consideration of the covenantor promise, which is the subject of suit, is the promise, the obligation to perform, and not the performance of the other covenant or promise. *2232 Chit. Con. 1082. But, if the performance of each covenant or promise is intended to be simultaneous, or concurrent, or a condition precedent to the performance of the other, performance, or a readiness to perform, or the hindrance of performance by tire other party, must be shown, to entitle either to claim performance from the other. — Jones v. Somerville, 1 Port. 437.
Whether promises or covenants are dependent or independent — whether performance, or readiness to perform, upon either side, must be concurrent, or is a condition precedent to the right of the other to enforce performance — is a question of frequent occurrence, and has been the matter of much discussion. There are rules recognized as useful, and applied in determining the intention of the parties— whether they intended-the covenants or promises should be dependent or independent. One of these, laid down by Sergeant Williams in his note to Pordage v. Cole (1 Wm. Saund. 481), is, that “if a day be appointed fpr payment of money, or part of it, or for doing any other act, and the day is to happen, or may happen, before the thing which is the consideration of the money, or other act, is to be performed; an action may be brought for the money, or for not doing such other act, before performance; for it appears that the party relied upon his remedy, and did not intend to make tbe performance a condition precedent; and so it is where no time is fixed for the performance of that which is the consideration of the money or other act.” An example of the application of the rule is given in the note : “ where articles of agreement were made between A. and B., and a covenant by A. that, for the consideration thereafter expressed, he should convey certain lands to B. in fee ; and B,, on his part, for the consideration aforesaid, covenanted to pay a sum of money to A.; it was held, that these were independent covenants, and A. might bring an action for the money before any conveyance of the lands.” This rule has been often recognized, and made the basis of decision in this court — Jones v. Somerville, supra; Ledyard v. Manning, 1 Ala. 153; Whitehurst v. Boyd, 8 Ala. 375; McKleroy v. Tulane, 34 Ala. 78.
An application of the rule to this contract, renders it certain that the payment of the purchase-money by Broughton was intended to precede, and was not dependent upon, the making of titles to him by McCall. A day certain' — the first of January, 1861 — is fixed for the payment of the purchase-money. No time is fixed for the making of titles — McCall is to make them, when, under the contract with his vendors, referred to in this contract, he shall have obtained them. Under that contract, McCall could not obtain title until he *224paid to his vendors the purchase-money in full; and'such payment he promised, and was bound to make, on the first day of January, 1862, twelve months after the time Broughton bound himself to pay McCall the purchase-money. It is apparent from the contract itself, that the parties could not have contemplated that Broughton’s promise to pay the purchase-money was dependent on making title to him. The day of payment, they knew, would precede the time when McCall would be able and ready to make title, and the day when Broughton could by right demand it. The case is, then, the one of very ordinary occurrence in this court, in which the vendee of lands, who has made an independent promise for the payment of the purchase-money, has been compelled to comply, though title has not been made to him.
6. We do not iuquire what decree should have been rendered, under appropriate pleading, as to compelling a compliance by McCall with his covenant to make title, if Broughton had tendered performance on his part. He was in possession of the lands, and could not resist the payment of the purchase-money because of his vendor’s failure or inability to make title. A cross-bill would have been the appropriate mode of obtaining title, if it had been desired, in performance of McCall’s covenant. There is no question that the title resides in the complainants, and when satisfaction of the decree for the purchase-money is made, they will probably be estopped from asserting it against Broughton.
7. Interest attaches, as matter of right, to a contract for the payment of money, from the day on which it becomes due. It is given by the statute, as a compensation for the detention of the money; and neither courts of law, nor of equity, have any discretion in its allowance. The chancellor erred in not computing interest on the purchase-money due from Broughton, from the first day of January, 1861, when it was payable. The agreed purchase-money in this case was $4,951.95, due and drawing interest from January 1st, 1861. The present bill was filed May 27th, 1874, thirteen years, four months, and twenty-nine days after the maturity of the debt. The chancellor, in his decree, adjudged that there was due to complainants the principal of the purchase-money, $4,951.95, and interest on that sum from the filing of the bill; making, of principal and interest, the sum of $5,5i9.65. This sum, with some small interest upon it, accrued after decree, the record informs us the defendant paid. The principal of the debt, and the interest which accrued on it after the bill was filed, has thus been paid, leaving unpaid the interest which accrued before the bill was *225filed. By calculation it is shown, that the sum of that interest was $5,313 when the present bill was filed. That sum the chancellor erroneously failed to award to the complainant, as part and parcel of the purchase-money due him. But it was interest, not principal, which the complainant failed to recover. We do not feel justified in applying the doctrine of rests to the payment made by Broughton under the chancellor’s decree. We regard it as payment of the principal, and partial payment of the interest. Interest does not draw interest, and it follows that the amount of the purchase-money due and unpaid, is the sum of the interest which had accrued when this suit was brought, without interest thereon up to the present time.
The result is, the decree on the appeal taken by Broughton must be affirmed. On the appeal taken by Mitchell and others, the decree must be reversed, and a decree here rendered in accordance with this opinion.