Recorded: May 29, 1967 and August 23, 1967
Chip Douglas has stated that the Monkees's "The Door Into Summer" was actually written solely by Bill Martin.
The title of the song is a reference to the Robert Heinlein novel of the same name.
The title was based on the Robert Heinlein’s book The Door Into Summer, which was about time travel. ‘The Door Into Summer’ is about the search for happiness and is basically an antiwar song.
-- Liner Notes for The Monkees Music Box collection
-  Citation Needed
-  Michael Nesmith. YouTube (2020-04-03) "Live Q&A" (https:/
/) youtu. be/ J7xNy- bMh5o