Complex sentence: Nevertheless, his understanding of corporeal substance was "thoroughly mechanistic;" his scientific work was based on the understanding of all natural objects, including not only billiard balls and rocks, but also non-human animals and even human bodies, as completely mechanistic automata.
Split into simpler sentences: Nevertheless, his understanding of corporeal substance was "thoroughly mechanistic". His scientific work was based on the understanding of all natural objects, including not only billiard balls and rocks, but also non-human animals and even human bodies, as completely mechanistic automata.