Read it through once

EMPEROR. Master Doctor Faustus,[132] I have heard strange report of thy knowledge in the black art, how that none in my empire nor in the whole world can compare with thee for the rare effects of magic: they say thou hast a familiar spirit, by whom thou canst accomplish what thou list. This, therefore, is my request, that thou let me see some proof of thy skill, that mine eyes may be witnesses to confirm what mine ears have heard reported: and here I swear to thee, by the honour of mine imperial crown, that, whatever thou doest, thou shalt be no ways prejudiced or endamaged.