Sentence:  Skill in invention, lucid arrangement and disposition of facts, are appreciated not by one passage, or by two, but gradually manifest themselves in the general structure of a work; but a sublime thought, if happily timed, <WSD>illumines</WSD> an entire subject with the vividness of a lightning-flash, and exhibits the whole power of the orator in a moment of time. 
Meaning of the word marked with <WSD> tags:  To illuminate.