Philosophy has always developed its thought through confrontation with poetry. Similarly, German philosopher Martin Heidegger's main imputes towards thinking of Being came from reflections on poetry, among which an eminent position was held by confrontation with the poetry of Romantic poet Friedrich Hölderlin. Through analysis of Heidegger's Elucidations of Hölderlin's Poetry, this thesis aims to demonstrate his thought on the essence of poetry. It becomes evident that, in order to comprehend it, the phenomena of speech, language and art need to be defined because they are interwoven with reflection on poetry. Through analysis of Being and Time, I therefore attempted to show how the phenomenon of speech is understood by the early Heidegger and to show, based on interpretation of the essays from On the Way to Language, his understanding of the phenomenon of language after the Turn. The phenomenon of speech is therefore set into the structure of Dasein as btheing-in-the-world, whereas language is included into thinking of truth as alétheie (unconcealment). Evidently, the essence of language is the articulation of words. Meanwhile, poetry or poetic composing is understood by Heidegger in the sense of disclosure of beings in their Being. Indicatively, the essence of poetry is perceived to be the founding articulation of Being. This essence enables the dwelling of a human being in world-game as well as the happening of Being in the Event.