The second part of Snorri Sturluson's Prose Edda the Skáldskaparmál or "language of poetry" (c. 50,000 words) is effectively a dialogue between Ægir, the Norse god of the sea, and Bragi, the god of poetry, in which both Norse mythology and discourse on the nature of poetry are intertwined. The origin of a number of kennings are given and Bragi then delivers a systematic list of kennings for various people, places and things. Bragi then goes on to discuss poetic language in some detail, in particular heiti, the concept of poetical words which are non-periphrastic e.g. steed for horse, and again systematises these. This in a way forms an early form of poetic thesaurus.