Arthur Miller gives us some insight into the octogenarian Giles Corey in his author's notes in act one of The Crucible. Giles is a rather comical and stubborn man, but he is also good-hearted and well meaning. He married his wife, Martha, later in life, and he also came to faith later in life. Unlike the Christian concept of prayer which is based on rather informal conversation with God, the Puritans learned their prayers and then had to recite them.
When Giles asks a question, it is because he wants to know the answer. He and Proctor seem quite different, but they think alike about many things. Before the Reverend Hale arrives, John is ready to leave Parris's house and asks Giles to come along. Giles says he wants to stay because he has "some few queer questions of my own to ask this fellow." Reverend Hale is well known for understanding witchcraft and being able to discern the mark of Satan when it is there. Giles respect this man of learning and wants to take advantage of this opportunity to talk to him.
When Giles finally gets the chance to ask his questions, this is what he asks:
Giles: Mr. Hale, I have always wanted to ask a learned man--what signifies the readin’ of strange books?
Hale: What books?
Giles: I cannot tell; she hides them.
Hale: Who does this?
Giles: Martha, my wife. I have waked at night many a time and found her in a corner, readin’ of a book. Now what do you make of that?
Hale: Why, that’s not necessarily--
Giles: It discomfits me! Last night--mark this--I tried and tried and could not say my prayers. And then she close her book and walks out of the house, and suddenly--mark this--I could pray again!
Hale: Ah! The stoppage of prayer--that is strange. I’ll speak further on that with you.
Giles: I’m not sayin’ she’s touched the Devil, now, but I’d admire to know what books she reads and why she hides them. She’ll not answer me, y’ see.
Giles is genuinely interested in the answers to his questions and in no way is implying anything about Martha and witchcraft. It is just something odd that he wonders about, and Hale is the one he asks.
What is probably true is that Giles is somewhat intimidated by his younger wife, someone who not only knows her prayers well but also reads regularly. Perhaps she hides her book so her husband will not feel bad because he cannot read. As a new convert, it is natural for him to stumble through his prayers at times--or even be too flustered by Martha's presence to speak at all. These questions are innocent and intended to be nothing more than genuine interest; however, in this environment of suspicion and accusation these questions could be seen as more than that.