I don't recall this being asked before, and it is something that I've wondered about for a while. On the "Heroes" album Bowie mentions one inch thoughts in Sons of the Silent Age and Secret Life of Arabia.
In Sons of the Silent age they "Search through their One Inch Thoughts and decide it couldn't be done"
In Secret Life of Arabia he writes that he went "Through one inch thoughts and fantasies".

What do you think he means? Can you give an example of what you think a one inch thought is, and do you know if Bowie ever explained this lyric?