Karl Birnbaum's 1945 naturalization certificate Click photo for larger image. Related Coverage: Holocaust archives inaccessible no longer

A slender, mustard-yellow volume sits on a shelf in my family's study. Its cheap cardstock cover is textured, unconvincingly, to resemble leather. "KARL BIRNBAUM: Leben und Werk" stretches across its front in a typeface one might see on the side of a Bauhaus building.

Below the title there are lines of dense text: "Inaugural-Dissertation, der Universitat zu Koln promoviert am 20. 12. 1982." The spine is breaking from the cardstock, and the cover must be opened gingerly to ensure that the brittle glue does not disintegrate. The dissertation is a biography of my great-grandfather. In its pages are buried the only records of my family's life in Germany before the war.

My grandfather, Ernst Birnbaum, rarely spoke of his life before America. He said that he had grown up an only child -- his brother had died very young from a disease. When pressed for more relatives, he said his parents had been only children too. My father was 14 before he realized his father had emigrated from Germany because he was Jewish.

In later years, Alzheimer's disease finally freed my grandfather's tongue. Still, the ramblings of the dying man contained only vague hints of grief and loss.

Those hints would be all we had if it were not for the mustard volume in the study. In the early '80s, two years after my grandfather died, my aunt received a phone call from a German medical student. He had just finished a doctoral dissertation about my great-grandfather, one of the first professors of psychiatry in Germany, and wanted to present a copy to Karl Birnbaum's descendants.

After two years of searching, he had tracked down our address in America. When the dissertation arrived in the mail, we put it on the shelf with my great-grandfather's books, and it has collected dust ever since, guarding its secrets in the code of German, a language my family no longer speaks.

I was proud of the dissertation when I was little, sure that if an ancient relative was worthy of attention, I was, too. I liked to see my last name in type. In kindergarten I once sneaked it to school for show-and-tell. When I brought it home, my father's anger surprised me. He did not like my handling the irreplaceable volume.

After that, I would wait until I was alone and seize my chance. The cover was bumpy under my fingers. There were only two pages I could understand: one, a reproduction of my great-grandfather's American naturalization certificate, made out to Carl (not Karl) Birnbaum, his "complete and true signature" looking strangely like my father's; and the other, his death certificate: April 17, 1950, in "Phila, Penna."

I read them over and over. I looked at the other pages, noticing the visual rhythm in their lines, whose capital letters were typed slightly lower than the lower-case ones, and I wondered what secrets were hidden in those impressive, endless words, with their punctilious umlauts and strange, looping Bs.

Four years ago, I mentioned the dissertation to my aunt. She groaned and said she hated its author. I could not understand why. She said he had told her things she would rather not know. I still did not understand. Her voice started to quaver, and she said that when the psychiatry student had called from Germany two decades ago, she had learned that her father had not grown up an only child after all -- that his brother had been murdered, in his twenties, during the war. She had never told anybody about that phone call. I felt myself needing the box of tissues she held in her hand.

Over the next few years, I struggled with the realization both that my family had been killed in the Holocaust and that my grandfather had denied it. At first I wished I had never known. If one thing was false, all was in question. What else lurked in the shadows? I found I could not eat bratwurst; see a black, red and gold flag; or hear "auf wiedersehen" without thinking of gas chambers. Even my favorite Beethoven symphony was lost: Wilhelm Furtwangler, a Nazi collaborator, conducted my recording.

I didn't want to burden others about my past, so I changed the topic whenever someone asked about my German last name. My only hope was that my grandfather had not lied outright but had simply made himself forget. As time passed and my shock diminished, I realized I needed to learn more.

Two years ago, I decided to visit Germany, and I got in touch with the author of the dissertation. I found him online--in his later years, he had taken to writing psychological crime thrillers.

He offered to fly from Cologne to Berlin to see me. I hadn't asked for a meeting, just the address of an old family home, so I accepted his offer with trepidation. The morning of the meeting, my girlfriend had to push me out the door of the hostel. We met him in the center of the city. He took us through the city a bit as we talked about everything besides my family, until finally we came to an outdoor cafe. We sat and he ordered beers.

He took a slim, mustard volume from his briefcase, and I was shocked by the recognition -- my father had always treated the dissertation with such care that I thought it was the only one in the world. Suddenly it dawned on me that the man must have a box full of them in his garage. He cracked it open. The spine popped and I cringed -- treat it with care, I wanted to tell him. Lives are in your hands.

With that, the now middle-aged man began to tell me the story of my family. I struggled to write it all down as a rough outline appeared. Yes, my great-grandparents had another son; Kurt-Gerhard was developmentally disabled, and my great-grandparents had been reluctant to leave Germany without him.

It was hard to keep taking notes. Yes, my great-grandfather had a sister -- she had written to America in 1941 to say that Kurt had been taken away and killed. The following year she died at Auschwitz. My pen shook. Another round of beers -- I had to accept for fear he would stop talking. Yes. My grandfather had sued Germany over his aunt and brother's deaths.

With this I laid down my pen. I could no longer blame my grandfather's omissions on confusion; his legal claims exposed his lies. I drank my beer to conceal my expression. Once the narrative was over, the man turned to the first page, cheerfully signed it "Dear Michael! All the best for you and your family" and pushed the book toward me.

To him, the book is a story of the war, one of many, an interesting if unhappy tale to be discussed over beer and ice cream on a sunny summer afternoon. But my family's story is not an abstract exercise in historical research. It is listening to my father deny, blank-faced, that he had an uncle, when I know that he did. It is hearing of my grandmother shortly before her death, in the middle of a psychotic episode, screaming that no, no, she's not harboring any Jews. It is fighting to remember when my family wants to forget.

Today I hold the thin volume in my hand and touch my fingers to its pages. I have started to learn German so I can study Jewish history -- not because of the book but in spite of it.

German class is a danger. Already subjects and verbs fall into place, I see the accusative case sprinkled across the text, and I understand the dative prepositions. Not speaking the language was my last, best hope for ignorance. Once I know German, the moment of weakness will come. I will pull the dissertation off the shelf, start reading, and be unable to stop.