Most contemporary scholars, although they disagree on other questions about the genesis of the poems, agree that the "Iliad" and the "Odyssey" were not produced by the same author, based on "the many differences of narrative manner, theology, ethics, vocabulary, and geographical perspective, and by the apparently imitative character of certain passages of the "Odyssey" in relation to the "Iliad"." Nearly all scholars agree that the "Iliad" and the "Odyssey" are unified poems, in that each poem shows a clear overall design, and that they are not merely strung together from unrelated songs. It is also generally agreed that each poem was composed mostly by a single author, who probably relied heavily on older oral traditions. Nearly all scholars agree that the "Doloneia" in Book X of the "Iliad" is not part of the original poem, but rather a later insertion by a different poet.