I have been connected with the Niels Bohr Institute since the completion of my university studies, first as a research fellow and, from 1956, as a professor of physics at the University of Copenhagen. After the death of my father in 1962, I followed him as director of the Institute until 1970.

Meaning: The timing of death cannot be treated as an appointment people can count on controlling. The calendar image expresses uncertainty about life’s duration, encouraging awareness of limits without making a prediction about any individual or demanding constant urgency.

Meaning: Death is imagined as unable to hear objections, so a protest cannot make it negotiate. The saying expresses mortality’s finality rather than a judgment about how someone should feel about loss.

Meaning: Death is named as a certainty against which other expectations seem less secure. The saying invites perspective on finite life, but it gives no information about anyone’s timing or circumstances and should not dismiss fear, grief or the value of present care.

Meaning: Death is possible at any age, while old age makes the end of life impossible to ignore. The contrast is a reminder of mortality.