Quote week turned into two weeks. That's cool with us if it's cool with you. We thought about acknowledging that in the title, but "Quote Fortnight" just doesn't have the same punch. So last week was quote week, and this week, too, is quote week. Right? Right.
When writing a paper with quoted sources, don't be afraid to utilize diverse sentence structures. Consider the following variations of the same quote:
a. "What is known can seldom be immediately told, and when it might be told, it is no longer known," writes Johnson on the subject of biography (116).
b. About biography, Johnson writes that "what is known can seldom be immediately told" (116), thus expressing both his discretions and his desire for intimate knowledge.
c. In the Life of Addison, Johnson further acknowledges the biographer's difficulties: "What is known can seldom be immediately told, and when it might be told, it is no longer known" (116).
d. "What is known," Johnson writes, "can seldom be immediately told, and when it might told, it is no longer known" (116).
Now: you could vary your constructions randomly, and it might work fine. More advanced writers, of course, report having a "sense" (or sometimes a "rhythm") that tells them which of the possible constructions follows smoothly from the previous sentence, or leads smoothly to the following sentence. The criteria for those kinds of decisions are complex and the subject of opinion. What we can say with certainty, though, is that if you use the exact same construction for every sentence in which you quote someone, many readers become bored. So why not switch it up?