Around 440 BC, philosophers Democritus and Leucippus proposed the atomic theory, suggesting that the universe is composed of indivisible particles called atoms. This revolutionary idea laid the foundation for modern atomic theory and influenced subsequent scientific thought. Their work emphasized the importance of reason and observation in understanding the natural world, marking a significant shift in philosophical inquiry.

Democritus's proposal of atomic theory around 440 BC laid the groundwork for materialist philosophy, which later influenced Lucretius's 'De Rerum Natura'. This philosophical framework resonated with Enlightenment and modernist poets who sought to articulate a vision of reality grounded in empirical observation rather than divine intervention.