He led life step by step down a path that took it from primeval simplicity to contemporary complexity, similar to Darwin’s evolutionary tree of life (fish begot amphibians who begot reptiles who begot birds and mammals, etc).
Yeye aliishi maisha yake hatua kwa hatua chini ya njia kwamba alichukua kutoka asili nyenyekevu hadi utata wa kisasa, sawa na maoni ya Darwin ya mabadiliko choro wa mti wa uzima (samaki akazaa amfibia ambaye alizaa nyoka ambaye akazaa ndege na wanyama, nk).