Who was meriwether lewis talking about when he reffered to the great father and great chief in his speech to the otoe?

When Meriwether Lewis was giving his speech to the Otoe and referred to the "great father" and "great chief" he was referring to their God as the "Great Father" and he called their chief the "Great Chief". He chose these descriptions to both sound boisterous and to make sure the natives developed a very favorable view of him.