Gorgias' extant rhetorical works – "Encomium of Helen" (Ἑλένης ἐγκώμιον), "Defense of Palamedes" (Ὑπέρ Παλαμήδους ἀπολογία), "On Non-Existence" (Περὶ τοῦ μὴ ὄντος ἢ Περὶ φύσεως), and "Epitaphios" (Επιτάφιος) – come to us via a work entitled "Technai" (Τέχναι), a manual of rhetorical instruction, which may have consisted of models to be memorized and demonstrate various principles of rhetorical practice (Leitch, et al. 29). Although some scholars claim that each work presents opposing statements, the four texts can be read as interrelated contributions to the up-and-coming theory and art ("technē") of rhetoric (McComiskey 32). Of Gorgias' surviving works, only the "Encomium" and the "Defense" are believed to exist in their entirety. Meanwhile, there are his own speeches, rhetorical, political, or other. A number of these are referred to and quoted by Aristotle, including a speech on Hellenic unity, a funeral oration for Athenians fallen in war, and a brief quotation from an "Encomium on the Eleans." Apart from the speeches, there are paraphrases of the treatise "On Nature or the Non-Existent." These works are each part of the Diels-Kranz collection, and although academics consider this source reliable, many of the works included are fragmentary and corrupt. Questions have also been raised as to the authenticity and accuracy of the texts attributed to Gorgias (Consigny 4).