Jenkins, J.
(After stating the foregoing facts.)
It is only the ruling stated in the 6th headnote that seems to require elaboration. While -counsel for plaintiff in the court below deny in their brief the allegations made by Johnson’s amended plea relative to the agreement alleged to have been entered into by them, they do not, of course, question the fact that the court below and this court, so far as the purposes of the demurrer are concerned, are bound to take as true each and every allegation therein set forth. Plaintiff’s counsel insist .that since the note sued on contains within itself no reference to any suretyship on the part of Johnson, and since neither the original plea nor the amendment shows that Johnson had given notice to Butler that he would seek to have the judgment framed so as to show that he, Johnson, was a surety only, and that since Butler is not in any way made a party to the defense set up by the amended answer claiming Johnson’s discharge by reason of the agreement releasing Butler, the court below was obliged to sustain its demurrer to the amended plea. We think, however, that the defense set up in the amendment to Johnson’s plea does not depend for its validity upon his relationship of surety on the note sued on, but that even if no such claim were made, and it could be shown that the plaintiff executed a valid release to Butler, Johnson, 'even though he were a joint principal, would thereby become discharged. See Campbell v. Brown, 20 Ga. 415; Powell v. Davis, 60 Ga. 70. Plaintiff also contends that inasmuch as the release set forth in the amended plea appears not to have been in writing, it was unenforceable as between the parties thereto, and. consequently can not operate as a release in favor of the other obligor, Johnson. We think, however, that an agreement of counsel authorized by his client, as is *533here alleged, even though not in writing, becomes binding when fully executed. Bradshaw v. Gormerly, 54 Ga. 557 (3); Wimberly v. Adams, 51 Ga. 433. It is also insisted that the amended plea is defective in that it does not show that the plaintiff itself ever had knowledge of the agreement alleged to have been entered into by its counsel, and th? t therefore, under the rule of law that knowledge is essential to ratification, the release is'not binding upon the plaintiff, and consequently does not bind Butler. But since the amended plea states specifically that the agreement was made by counsel with full authority from the plaintiff, we do not think the doctrine here invoked is applicable, which is to the effect that the unauthorized act of an agent becomes binding when with full knowledge of the facts it is ratified by the principal. Lamplcin v. First National Bank, 96 Ga. 487 (33 S. E. 390). The point involving the greatest difficulty to the writer has been to determine whether or not the alleged release set forth in the amended plea was, under the averments as therein made, founded upon a consideration. That a consideration must exist in order to make valid such a release has been decided many times by the-Supreme Court and also by this court. Bruton v. Wooten, 15 Ga. 570; Stamper v. Hayes, 35 Ga. 546; Molyneaux v. Collier, 30 Ga. 731; Fowler v. Coker, 107 Ga. 817 (33 S. E. 661); Williams-Thompson Co. v. Williams, 10 Ga. App. 351 (73 S. E. 409). If, for the lack of consideration, the alleged release is not binding upon either of the parties thereto, it would not afford the basis of a discharge in favor of Johnson, the other obligor. We fully agree with counsel for plaintiff in their, contention that the failure to make Butler a party defendant in the former writ of error did not render that bill of exceptions subject to dismissal, and therefore we do not think any benefit whatever inured to the plaintiff by reason of the fact that Butler consented to be made a party defendant to it. See Wyche v. Greene, 16 Ga. 47; McGaughey v. Latham, 63 Ga. 67 (3); Fining v. Georgia By. & El. Co., 133 Ga. 458, 463 (66 S. E. 337); Bank of Covington v. Cannon, 133 Ga. 779 (67 S. E. 83). The definition of a consideration in section 4343 of the Civil Code (1910) is as follows: “A consideration is valid if any benefit accrues to «him who makes the promise, or any injury to him who receives the promise.” So while it is thus true that no possible benefit accrued to the plaintiff *534by reason of Butler consenting to bepome a party defendant to the former writ of error, still, if it be true that by reason of the execution of.such alleged agreement any injury resulted to Butler, such injury to him would afford a consideration for the agreement, just as sufficient as would a benefit flowing to plaintiff. If Butler, upon the agreement made for his release, consented to be made a party defendant to the former writ of error, as set forth by the amended plea, he thereby subjected himself to liability for the cost of the writ of error, and by assuming that risk he in law became injured through the consummation of the alleged agreement. While this contention is set forth by the defendant in the brief of his counsel, it is true that it is not thus stated in the amended plea; hut, since this result necessarily follows as a matter of law from the statement of facts therein set forth, no necessity existed for outlining in the plea the reason why a valid consideration existed, where, from the statement of facts, it necessarily follows as a legal consequence. It is for this reason that we think the plea as amended shows that the alleged agreement was based upon a legal consideration, and not because of any possible benefit flowing to plaintiff therefrom.
Judgment reversed.
Wade, G. J., and Harwell, J., concur. Harwell, J., was designated to preside instead of Lulce, J., who was disqualified.