Derek Parfit's Reasons and Persons
Morton footnotes this as associated with the following set of propositions:
over a long enough time scale, two things will be true:
"No one will be meaningfully related to me" and "Every action I do now will have a greatly amplified significance"
shades of Daisy Hildyard's The Second Body, which also dwells on this amplified significance (I am, at times, skeptical of this proposition)
"My effects on the world will have been immense. But I qua Tim Morton won't matter at all."