  It is convenient to start with Anaxagoras, who, though not generally counted as a sophist, in that he did not offer instruction in how to live or teach rhetoric, nevertheless shared the scientific interests of sophists such as Hippias, and personified the growing rationalistic approach to natural phenomena. When he said that the sun was a molten rock, larger than the Peloponnese (Diogenes Laertius II.8, cf. Plato, Apology 26d), he did mean that it was nothing other than a rock, i.e., not a divine being, and he was rightly considered as challenging traditional views of natural phenomena as divinely significant. Plutarch’s story (Life of Pericles 6) of the one-horned ram neatly encapsulates the opposed world-views: a ram with one horn in the middle of its forehead was brought to Pericles, and the soothsayer Lampon interpreted it as a portent signifying the forthcoming triumph of Pericles in his political struggle with his rival Thucydides. Anaxagoras dissected the animal’s skull and showed that the single horn grew naturally out of a deformity of the brain. So, Plutarch reports, the people admired Anaxagoras (but admired Lampon even more when Thucydides was ostracized soon afterwards). The naturalistic approach to meteorology etc. is not as such inconsistent with belief in divinities, and though Anaxagoras does not explicitly describe his cosmic Nous as divine, his description of it as knowing, controlling and organizing everything (DK 59B12) strongly suggests that he thought that it was. Among the phenomena for which reductive explanations were offered in the fifth century was the origin of religious belief itself. There is an indication of this in Democritus DK 68B30 (preserved by Clement of Alexandria): ‘A few learned people, holding up their hands towards what we Greeks now call the air, said “Zeus thinks of all things and he knows all things and gives and takes away, and he is king of all things” ’, which is supported by the testimony of Sextus (Against the Mathematicians IX.24) that Democritus said that belief in gods arose when primitive people were frightened by thunder, lightning and other celestial phenomena. An alternative account, or rather two accounts, equally reductive, of the origin of religion is attributed to Prodicus, who is reported by various sources as holding that the names of gods were originally applied either to things which are particularly important in human life, such as the sun, rivers, kinds of crops etc., or else to the people who had originally discovered things of that kind (DK 84B5). It was presumably on the basis of this that Prodicus was counted as an atheist in antiquity (Aetius I.7.1, Cicero De Natura Deorum I.42.117); he was understood, probably rightly, as meaning that in fact Demeter is nothing but corn, Dionysus nothing but wine, and so on. Most commentators agree that Prodicus was an atheist of some kind (for a dissenting view see Sedley 2013, at 329–331), but there is some division of opinion on whether the atheism which he espoused was radical atheism, i.e. denial of the  existence of divine beings of any kind, or a more moderate version which denied the existence of the gods of popular and poetic tradition while allowing the divinity of cosmic items such as the heavenly bodies, water etc. (on the issue see Mayhew 2011, xvii, 183–4).  (For more recent discussions of Prodicus’ views on religion, and of their connection with his views on cosmology and language see Kouloumentas 2018, Lebedev 2019 and Vassallo 2018.)