Answer:
William Sumner was a sociology teacher, who wrote an essay called ''Sociology'', through that paper he explain the sense that give direction to society. In first place, he said that man only wants to satisfy his needs, this is a biological impulse (he wrote about sociology with a biology point of view), so mankind will even fight against nature to survive.
Soon or later, men are gonna fight against men, because natural resources are limited. In this case, he define ''poor people'' like those whom don't effort enough to satisfy their needs, and ''rich people'' are those whom are determined to succeed with their hardwork.