I first saw these in Béla Bollobás’s Foreword to Littlewood’s miscellany. Adapted from a lecture given by Harald Bohr on his 60th birthday in 1947. Published in his Collected works.
- When one writes to the other, it was indifferent to whether what was said was right or wrong. This allows one to be free in discussion ideas without any sense of responsibility.
- When one received a letter from the other, they were under no obligation to read it, let alone to answer it.
- "[A]lthough it did not really matter much if they both thought about the same detail, still, it was preferable that they should not do so."
- "[I]t was quite indifferent if one of them had not contributed the least to the contents of a paper under their common name; otherwise there would constantly arise quarrels and difficulties in that now one, and now the other, would oppose being named co-author."