  In his 1948 lecture to the British Interplanetary Society, Olaf Stapledon
considered the ultimate purpose of colonising other worlds. Having examined the
possible motivations arising from improved scientific knowledge and access to
extraterrestrial raw materials, he concludes that the ultimate benefits of
space colonisation will be the increased opportunities for developing human
(and post-human) diversity, intellectual and aesthetic potential and,
especially, 'spirituality'. By the latter concept he meant a striving for
"sensitive and intelligent awareness of things in the universe (including
persons), and of the universe as a whole." A key insight articulated by
Stapledon in this lecture was that this should be the aspiration of all human
development anyway, with or without space colonisation, but that the latter
would greatly increase the scope for such developments. Another key aspect of
his vision was the development of a diverse, but connected, 'Commonwealth of
Worlds' extending throughout the Solar System, and eventually beyond, within
which human potential would be maximised. In this paper I analyse Stapledon's
vision of space colonisation, and will conclude that his overall conclusions
remain sound. However, I will also argue that he was overly utopian in
believing that human social and political unity are prerequisites for space
exploration (while agreeing that they are desirable objectives in their own
right), and that he unnecessarily downplayed the more prosaic scientific and
economic motivations which are likely to be key drivers for space exploration
(if not colonisation) in the shorter term. Finally, I draw attention to some
recent developments in international space policy which, although probably not
influenced by Stapledon's work, are nevertheless congruent with his overarching
philosophy as outlined in 'Interplanetary Man?'
