The physicist–philosopher Philipp Frank’s work and influence, especially during his last three decades, when he found a refuge and a position in America, deserve more discussion than has been the case so far. In what follows, I hope I may call him Philipp – having been first a graduate student in one of his courses at Harvard University, then his teaching assistant sharing his offices, then for many years his colleague and friend in the same Physics Department, and finally, doing research on his archival holdings kept at Harvard. I also should not hide my large personal debt to him, for without his recommendation in the 1950s to the Albert Einstein Estate, I would not have received its warm welcome and its permission, as the first one to do historical research in the treasure trove of unpublished letters and manuscripts, thus starting me on a major part of my career in the history of science.