"My four little children will one day live in a nation where they will not be judged by the color of their skin but the content of their character." In this MlK is showing that the race of an individual is not what describes their welling being and the person who they are, It is consider Pathos because it really tells the audience that world we lived in was one where the color of skin makes you who you are.
"Architects of our republic wrote the magnificent words of the Constitution and the Delcaration of Indendence, they were singing s promissory note to which every american was to fall heir." when saying this MLK is using the constitution and Declaration of Independence to show that it is not made up and convincing his audience using sources.
"To realize that their destiny is tied up with out destiny." He is trying to inform the audience that just because the color of skin may be different it does not mean that they are a different person and do not have goals.