Significant and fascinating TLS signed “A. Einstein,” one page, 7 x 8.5, January 5, 1934. Einstein writes to the imprisoned Nathan Leopold, Jr. of the notorious gay Jewish “thrill-killing” couple whose trial for the kidnapping and murder of Chicago fourteen-year-old Bobby Franks was one of the most sensational news events of the 1920s. The conviction of Leopold and his associate, Richard Loeb, earned the duo lasting infamy in the annals of crime, and their deeds inspired at least three films, including Hitchcock’s Rope (1948) and the classic Orson Welles starrer Compulsion (1959). Einstein writes to the intellectually voracious Leopold, then serving his term of life plus ninety-nine years (he was paroled in 1958), in full: “May I advise you not to attempt to achieve your goal too directly, but first to read a scientific book on Mechanics and on Electrodynamics. They should preferably be books which use higher mathematics (calculus) and which are not too long; for instance, the lectures by Planck. I am sorry that I do not know the English textbooks, but you should ask someone for advice who is familiar with them. When you are through with these books, it should be easy for you to study relativity; for instance, the collection of the original statements Lorentz-Einstein-Minkowski, the textbook by Kopff which as far as I know is translated into English, and the mathematical book on relativity by Eddington.” In very good to fine condition, with a prison censor’s ink stamp at bottom right, light uniform toning, a few light creases, and the two top corners, including a small hole, skillfully repaired. COA John Reznikoff/PSA/DNA, PSA/DNA and R&R COA.