On several occasions, Derrida has acknowledged his debt to Husserl and Heidegger, and stated that without them he would not have said a single word. Among the questions asked in these essays are "What is 'meaning', what are its historical relationships to what is purportedly identified under the rubric 'voice' as a value of presence, presence of the object, presence of meaning to consciousness, self-presence in so called living speech and in self-consciousness?" In another essay in "Writing and Difference" titled "Violence and Metaphysics: An Essay on the Thought of Emmanuel Levinas", the roots of another major theme in Derrida's thought emerges: the Other as opposed to the Same "Deconstructive analysis deprives the present of its prestige and exposes it to something "tout autre", "wholly other," beyond what is foreseeable from the present, beyond the horizon of the "same"." Other than Rousseau, Husserl, Heidegger and Levinas, these three books discussed, and/or relied upon, the works of many philosophers and authors, including linguist Saussure, Hegel, Foucault, Bataille, Descartes, anthropologist Lévi-Strauss, paleontologist Leroi-Gourhan, psychoanalyst Freud, and writers such as Jabès and Artaud.