Structure of the Earth the crust, upper mantle, lower mantle, outer core, and inner core. The geologic component layers of Earth are at the following depths below the surface: The layering of Earth has been inferred indirectly using the time of travel of refracted and reflected seismic waves created by earthquakes. The core does not allow shear waves to pass through it, while the speed of travel (seismic velocity) is different in other layers. The changes in seismic velocity between different layers causes refraction owing to Snell's law, like light bending as it passes through a prism. Likewise, reflections are caused by a large
The Ego and Its Own is certainly true that we must first make a cause our own, egoistic cause, before we can do anything to further it. . . . [W]e are communists out of egoism also, and it is out of egoism that we wish to be human beings, not mere individuals... However, Marx and Engels would later collaborate on a lengthy criticism of Stirner's book in "The German Ideology" (1845, published 1932). The critique is a polemical tirade filled with ad hominem attacks and insults against Stirner (Marx calls him a "petty bourgeois individualist intellectual"). Stirner also had a lasting influence in the