Sentence:  A contrast of the scripture reading of , let us say , St. Augustine , John Bunyan , and Thomas Jefferson , all three of whom found in such study a real source of <WSD>enlightenment</WSD> , can tell us a great deal about these three men and the age that each represented and helped bring to conscious expression . 
Meaning of the word marked with <WSD> tags:  education that results in understanding and the spread of knowledge