A goal of Epicurean philosophy was the achievement of calm and freedom from anxiety. Epicurus believed that if people can be freed from fear - including fears relating to the actions of gods - they can then achieve ataraxia ('being undisturbed'). Epicurean cosmology and meteorology were motivated by the desire to alleviate fear of gods. While Epicurus recognized the existence of gods, he denied the possibility that they have any cosmic influence. He developed a strict materialist philosophy, designed to offer natural explanations of phenomena that were often seen as due to activities of gods. Questions about the origin and order of the world, its possible beginning and end, are potentially disturbing: violent natural phenomena, particularly thunder, lightning, hail and earthquakes, can be terrifying and destructive. If such phenomena are not due to gods, there is no reason to fear the gods' involvement in our world. Epicurean meteorology explained the meteōra (the phenomena of the sky, and earthquakes); cosmology focused on the nature of our local cosmos (kosmos), while acknowledging the existence of an infinite number of kosmoi (worlds). The Greek word kosmos carried a range of meanings; its use in natural philosophy was coloured by the worldview of the user.