abstract object abstraction an essay concerning human understanding apperception aristotle arthur schopenhauer bertrand russell brainstorming bryan magee centaur cognition concept consciousness contradiction copyright creativity techniques david hume determinism diffusion of innovations distinction empirical everett rogers evolution evolutionary biology experiment fish gene horse hypothesis idea-expression divide idealism ideology image imagination immanuel kant inspiration intellectual property introspection intuition james boswell john locke john stuart mill karl popper knowledge law liberty list of perception-related topics ludwig wittgenstein man meditations on first philosophy meme memory mental image mermaid metaphysics mind neoplatonism nous object of the mind opinion patent perception philosophy plato platonic epistemology plotinus pragmatism process property psychologist public domain real life reality reason reflection richard dawkins rudolf steiner samuel johnson schaff-herzog encyclopedia of religious knowledge science selection separation solipsism tabula rasa the future of ideas theory of forms think tank thomas aquinas thought thought experiment truth validity vernacular walk of ideas wikibooks wikiquote wikisource wikiversity wiktionary woman