款識：
天馬徠，從西極，涉流沙，九夷服。
幻蓀先生作山水，獨能師法造化，空谷足音，殊欣聲應氣求之，感蒙惠畫扇，寫此答之，匪敢云報也。丁亥大暑。悲鴻。

鈐印：「江南布衣」、「永以為好」。

-Light foxing, especially in the upper section of the paper, two creases at top and bottom, and white pigment at the horse nose flaking off can be found, which can be improved by restoration. Otherwise, generally in good condition.
"In response to your inquiry, we are pleased to provide you with a general report of the condition of the property described above. Since we are not professional conservators or restorers, we urge you to consult with a restorer or conservator of your choice who will be better able to provide a detailed, professional report. Prospective buyers should inspect each lot to satisfy themselves as to condition and must understand that any statement made by Sotheby's is merely a subjective, qualified opinion. Prospective buyers should also refer to any Important Notices regarding this sale, which are printed in the Sale Catalogue.
NOTWITHSTANDING THIS REPORT OR ANY DISCUSSIONS CONCERNING A LOT, ALL LOTS ARE OFFERED AND SOLD AS IS" IN ACCORDANCE WITH THE CONDITIONS OF BUSINESS PRINTED IN THE SALE CATALOGUE."

上款：「幻蓀」即吳幻蓀（1905-1975），北京人，青年時期參加湖社畫會，畢業於私立朝陽學院。他研究北宗山水畫法，致力於寫生，融合西法。歷任北京多所大專院校教師。

註：一九四六年徐悲鴻應國民政府教育部之聘，北上擔任國立北平藝專校長。其時北平一地藝術思潮紛呈，或保守傳統，或崇尚西洋，難免互有相左之處，徐悲鴻之責任、理想則在振興藝術，消除門戶隔閡，促使中西藝術思潮融貫，故與當地文化界人士廣為往來。他在本幅題曰「聲應氣求」、「感蒙惠畫扇」，措辭極為親切、謙遜之心可見。時吳幻蓀雖為風格較為保守的北平市美術會常務理事，但與徐悲鴻仍關係良好，一九四七年四月，徐氏為裱畫師劉金濤籌措資金擴充門面，發起義賣畫展，吳幻蓀亦提供作品。悲鴻贈吳氏本幅約兩月後，北平即掀起一場「國畫論爭」，與之對立的張伯駒正是北平市美術會理事長，然翌年四月國立北平藝專慶祝三十周年紀念活動中，吳仍作為來賓致辭，徐、吳交誼由此可見一斑。