Wanderlust: A History of Walking (2001) 
Source: Storming the Gates of Paradise: Landscapes for Politics 
Context: Walking has been one of the constellations in the starry sky of human culture, a constellation whose three stars are the body, the imagination, and the wide-open world, and though all three exist independently, it is the lines drawn between them—drawn by the act of walking for cultural purposes—that makes them a constellation. Constellations are not natural phenomena but cultural impositions; the lines drawn between stars are like paths worn by the imagination of those who have gone before. This constellation called walking has a history, the history trod out by all those poets and philosophers and insurrectionaries, by jaywalkers, streetwalkers, pilgrims, tourists, hikers, mountaineers, but whether it has a future depends on whether those connecting paths are traveled still.
                                    
“It’s a map of a non-existent coast under an imaginary constellation on an impossible sky in—” he grunted, twisting something—“the middle of a ring of meaningless numbers. That’s why it’s powerful. That’s why it’s magic.”
Source: Neveryóna (1983), Chapter 12, “Of Models, Monsters, Night, and the Numinous” (p. 365)
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Samuel R. Delany 131
American author, professor and literary critic 1942Related quotes
“In principio it is impossible to prove from experiments that something is non-existent.”
The Magnetic Current http://adsabs.harvard.edu/abs/1941Sci....94..232E, Science, Volume 94, Issue 2436, pp. 232-233 (September, 1941)
                                        
                                        Principles of Mathematics (1903), p. 450 
1900s
                                    
“An invention is something that was “impossible” up to then—that’s why governments grant patents.”
Source: The Door Into Summer (1957), Chapter 6
Creation Myths (1995) 'Chains' (Genealogies), p. 326 Shambhala ISBN 0-87773-528-X
Source: 1970s, Take Today : The Executive as Dropout (1972), p. 114