An Essay on the Principle of Population T.R. Malthus, Leviathan Thomas Hobbes, The Social Contract and Discourse by Rousseau, Psychology of the Unconscious by Carl G. Jung, mint condition, gold bound, red, navy blue. An Essay on the Principle of Population T.R. Malthus, Leviathan Thomas Hobbes, The Social Contract and Discourse by Rousseau, Psychology of the Unconscious by Carl G. Jung, mint condition, gold bound, red, navy blue.