Final answer:
The figurative language used in the quote is personification, where Nature is personified as if it can speak and acknowledge the greatness of the person's life.
Step-by-step explanation:
The figurative language used in the quote, 'His life was gentle, and the elements so mixed in him that Nature might stand up and say to all the world, 'This was a man!'' is personification.
Personification is a figure of speech in which non-human entities or abstract ideas are given human characteristics. In this quote, Nature is personified as if it has the ability to stand up and speak, emphasizing the greatness and harmony of the person's life.