Continuing on this topic, Aristotle observed that whatever people do, the end result they wish to achieve is always the same: happiness. He also points out that "collecting butterflies, climbing mountains, or reading lots of books" is always done to make that person happy. He argued that happiness is a rational activity that belongs to human functionality, is pursued as an end in itself, is sufficient and is the common denominator of all these varied activities that we carry out; therefore it must be the goal of all reasons, the supreme good for the human being