The plaintiff, an architect, recovered a verdict from the defendant for “services rendered in drawing sketches ... in connection with the building of a house.” Against the defendant’s exceptions, the plaintiff introduced in evidence a letter from the defendant to the plaintiff, dated September 12, 1917, and also a letter from the plaintiff to the defendant, dated September 10, 1917. The plaintiff also was permitted to put in evidence a bill for his services dated September 15,1917.
The letter of September 10 from the plaintiff to the defendant was a declaration in the plaintiff’s favor. It was a self-serving document. The plaintiff could not make evidence for himself by-writing such a letter and mailing it to the defendant; it could not be used to establish his case. Fearing v. Kimball, 4 Allen, 125, 127, 128. Percy v. Bibber, 134 Mass. 404.
If the defendant failed to answer the letter, his failure would not make the letter admissible. Kumin v. Fine, 229 Mass. 75. Callahan v. Goodwin, 216 Mass. 234. The reference to the letter of September 10, and the acknowledgment of its receipt contained in the letter of September 12, are not sufficient to make the plaintiff’s letter admissible. Smith v. Abbott, 221 Mass. 326, 331. Percy v. Bibber, 134 Mass. 404.
A self-serving letter may become admissible when its statements are agreed to by the adverse party, but there was nothing in the letter of September 12 which could be construed to mean that the defendant admitted the truth of the plaintiff’s statements Commonwealth v. Eastman, 1 Cush. 189, 215. Pye v. Perry, 217 Mass. 68, 71. The fact that the letter of September 12 was admitted in evidence before the letter of September 10 was offered, did not make the latter competent. The order of proof did not change the rule of evidence. As the letter of September 12 did not amount to an admission by the defendant that the recitals in the letter of September 10 were true, the defendant’s letter could not be used as a foundation to make the plaintiff’s letter competent. Neither was the plaintiff’s letter competent to explain, qualify or aid in the construction of the defendant’s letter under the rule explained in Buffum v. York Manuf. Co. 175 Mass. 471, and similar cases.
*588As there was error in admitting the letter of September 10, and the defendant may have been harmed thereby, it is unnecessary to consider the question whether' there was any reversible error in admitting the letter of September 12 and the bill of September 15.
Exceptions sustained.