When Albert Einstein lay dying in Princeton Hospital, the nurse assigned to him spoke no German and the great physicist's last words passed uncomprehended. Strangely, for a person of such interest and eminence, the rest of his legacy has long remained almost equally inaccessible. Publication of his papers has begun only now, after a 30-year delay, and even then with an English translation supplied as a grudging afterthought. His brain was removed for a scientific study that has yet to be published.

Einstein died on April 18, 1955. It took until 1976 to choose an editor for his papers. Litigation then arose between his executor, Otto Nathan, who wanted three editors, and Princeton University Press, which preferred one. Princeton prevailed, and the first volume appeared this May, transformed by 50 recently discovered letters about love and physics between the young Einstein and Mileva Maric, a Serbian student who became his first wife. The letters describe Einstein's mother's intense disapproval of Mileva, who was the wrong age, the wrong class and, needless to say, not Jewish.

The documents, notes Gerald Holton, a historian of science, also portray ''a mind sharpening its tools, a young man of 22 beginning to ask fundamental questions, an intellectual giant awakening.'' Might anyone besides German-speaking scholars be interested in such an archive? Princeton didn't think so. Only at the insistence of the National Science Foundation, a supporter of the project, has an English translation been prepared. But the publisher sells it only to those who purchase the German edition as well.

As for Einstein's brain, the learned anatomists who had it removed for study could not agree how to dissect it. The organ passed into the possession of Thomas S. Harvey, the pathologist who performed the autopsy. In 1976 a reporter tracked down Dr. Harvey in Wichita, Kan. He still had the brain in his office, stored in glass jars, in a box labeled ''Costa cider.'' Dr. Harvey, now in Weston, Mo., says he hasn't yet decided on the brain's ultimate disposition.