Heinlein And Anderson

I am still contemplating a comparison between Robert Heinlein's Future History and Poul Anderson's Time Patrol series:

two long sf series;

each can be collected in two long volumes (also true of Anderson's Psychotechnic History);

both deal with history;

both convey a sense of adventure about the immediate future;

each has a historical culmination, the Danellians and the "first mature culture."

Anderson has:

immortals living through history, then through the present and into the future in The Boat Of A Million Years;

several future histories;

time travel in several works, including one that intersects with a future history.

Heinlein has a time travelling immortal, Lazarus Long, in his Future History - if we accept Time Enough For Love as a valid addition to the Future History, which I don't.

However, Lazarus is in Volume IV of the Future History and time travel is hinted at in the Time Chart. The section of Time Enough For Love where Lazarus time travels is called "Da Capo," which is also the title of the very last item in the Time Chart, one of the "Stories-to-be-told," although Heinlein does not mention or discuss this potential narrative in his "Concerning Stories Never Written." It looks as if Heinlein had already thought of someone time travelling from the very end of the series although it would have made sense to include "Da Capo" at the beginning as well as at the end. A spear-carrying character, like a spaceship captain, in The Green Hills Of Earth could have turned out to be an earlier alias of Lazarus. It puzzled me to see Lazarus' lifespan extending right through the Time Chart in Volume I but all was explained in Volume IV.

Read the Future History but then read Anderson's future histories and Time Patrol.