People throughout history have kept personal diaries, and some have even made their names primarily through working as diarists. More unusual, however, are those who penned their innermost thoughts in secret code. But she also kept a series of diaries in a code of her own making from the age of 15 to 30. This led him to decode a nearby word as “execution.” Linder was then able to unlock the rest of Potter’s secret code relatively quickly. But parts of his inner world remained a mystery, as sections of a private diary Roosevelt kept in his early twenties were written in a secret code.