"I have been studying your work on Relativity with great interest"
Important English mathematician, logician, and philosopher (1861-1947) who co-authored the three-volume Principia Mathematica with Bertrand Russell. Rare ALS signed “A. N. Whitehead,” one page, 6.25 x 6.25, personal letterhead (struck through with his new address written in the upper right), June 13, 1918. Handwritten letter to Dr. Ludwik Silberstein, in full: "I have been hoping to find some off-prints of my paper on math concepts etc.—my papers are in some confusion owing to recent removals both in my private house and college rooms—now that lectures are over I will make a more systematic search. I have been studying your work on Relativity with great interest." Silberstein notes the dates of receipt and reply in the upper right. In very good to fine condition, with irregularly trimmed edges.