Plato's world of eternal and unchanging Forms, imperfectly represented in matter by a divine Artisan, contrasts sharply with the various mechanistic Weltanschauungen, of which atomism was, by the fourth century at least, the most prominent..
In this period, some metaphysical naturalists adhered to a distinct doctrine, materialism, which became the only category of metaphysical naturalism widely defended until the 20th century, when advances in physics resulted in widespread abandonment of prior formulations of materialism.