Here are the contexts of the quotes tweeted from @sueannbowling from October 24 through October 30, 2013.
“To be a guardian of Power—one did not remain unchanged!” ‘Ware Hawk, by Andre Norton. Tirtha, after she has guarded the Power her family has taken responsibility for.
“Do not be too sure that possession of Power is always a gift.” Songsmith, by Andre Norton and A. C. Crispin. Alon to Eydryth, when he realizes that she is part of a family with Power.
“Magic does indeed wear hardly upon the user.” Songsmith, by Andre Nortonand A. C. Crispin . Eydryth, when she realizes that Alron has paused to use his magic to help them.
“Many things of the Light have their dark shadows.” Songsmith, by Andre Norton and A. C. Crispin. Alon, warning Eydryth that even a Power of the Light can be dangerous.
“Without belief and faith, Power is nothing.” Songsmith, by Andre Norton and A. C. Crispin. Eydryth, realizing that Alon must believe in himself if his magic is to win them free.
“If he can thus mark the true path for us, then we will be able to escape this maze.” Songsmith, by Andre Norton and A. C. Crispin. Eydryth, as Alon uses his Power to indicate their true way through the illusions.
“What are we supposed to hold on to?” Tourist Trap, by Sue Ann Bowling. Timi has his doubts about tackling the peccary.