The word absence is strongly polysemic. It indicates a state or condition in which something expected, wanted, or looked for is not present or does not exist; a failure to be present at a usual or expected place but also an inattention to present surroundings or occurrences. The multiplicity of meanings lends itself well to reflect the plurality of forms of absence that distinguishes, in the long run, the collective history of mathematicians who fled for political and racial reasons. To understand when and why a name is missing from a list of aspiring exiles, it is rarely enough to invoke a purely scientific motivation. Other factors come into play: painful choices, forced decisions, human participation, distress, etc. There were several reasons behind failed emigrations: some scholars moved too late, or made errors of judgement, for example by declaring in their curriculum their fascist merits; others were not internationally renowned or dealt with mathematical disciplines that were considered marginal or of little interest. Many would-be refugees were early career scholars. Age and gender were two discriminating factors.