There are 2 parts.. what were daniel hale williams motivations? and how did daniel hale williams contribute to science?

Daniel Hale Williams' motivations were to succeed in the first heart surgery and to overcome discrimination.

He contributed to science by helping advance the needed technology for heart surgeries-- after he complete the first ever heart surgery, scientists looked into antibiotics and proper technology so the heart surgeries in the future would be much more easier.

credit should be the answer

the answer is:  

he is voicing feelings shared by all humans regardless of race.

in paul laurence dunbar's poem "we wear the mask," he replicates the words mask and we to emphasize how people in general -not just black americans- hide their true feelings. he suggests the masks cover people's faces and eyes, which are the main parts that display their emotions. he also thinks people's pain conceal behind those masks, so that they cannot see reality and nobody is able to see one another's sorrow.