Adam Smith (1817). “The Theory of Moral Sentiments: Or, An Essay Towards an Analysis of the Principles by which Men Naturally Judge Concerning the Conduct and Character, First of Their Neighbours, and Afterwards of Themselves : to which is Added, A Dissertation on the Origin of Languages”, p.379
"We'll Never Conquer Space". Essay by Arthur C. Clarke first published in "Science Digest" (June 1960); later published in Arthur C. Clarke "Profiles of the Future: An Inquiry into the Limits of the Possible", 1962, in Arthur C. Clarke "Voices from the Sky", 1965, and in Arthur C. Clarke "Greetings, Carbon-Based Bipeds!: Collected Essays, 1934-1998", 1999.