Sentence:  And He laid down for him certain <WSD>conditions</WSD> : so that , if he kept the command of God , then he would always remain as he was , that is , immortal ; but if he did not , he would become mortal , melting into earth , whence his frame had been taken '' . 
Meaning of the word marked with <WSD> tags:  an assumption on which rests the validity or effect of something else