"So far as I can recollect I have always been a man, a man of about thirty." A Princess of Mars by Edgar Rice Burroughs
These is more to John Carter than just astrally projecting to Mars/Barsoom. He doesn't seem to age and doesn't remember his childhood. This could possibly be influence from Edwin Lester Arnold's Phra the Phoenician, another un-aging character.
Here's how Third Sentence Thursday works:
1) Take the book you are reading now and post the third sentence
2) Review this sentence anyway you want (funny and silly reviews encouraged)
3) Post a link to your sentence to Sniffly Kitty's Third Sentence Post for this week.