'But if thine eye be evil, thy whole body shall be full of darkness. If therefore the light that is in thee be darkness, how great is that darkness!' _ an attempt to inspire to move into light and not use power for black or selfish deeds... when black and selfish deeds are in fact a product of internalised fear... cyclical and unuseful to preach such bla bla - however can be clarifying for some.
'If one's eye is diseased, all he sees is wrong. So the mind, or conscience, is the light of the soul. If these be darkened, all is darkness; if these see aright, all is light.'
Basically, a pure innocent and undistorted heart will produce light, and great light. A heart is naturally pure, any impurity, is created by the self cherishing and ignorant ego... burn it away with practice, become whole and you will become illumined for we are all born to evolve into conscious light beings..:D