One ancient theory was an idea called vitalism, which claimed that living things were unique because they were filled with a special substance, or energy, that was the essence of life. 
یک نظریه باستانی به نام "حیات گرایی" ادعا میکند که موجودات زنده بی نظیر هستند چون آکنده از مواد یا انرژی خاصی بوده که جوهر و ماهیت زندگی است. 