A.T. Robertson Commentary John 4:19

"The woman saith unto him, Sir, I perceive that thou art a prophet." — John 4:19 (ASV)

Sir (Κυριε). So still.

I perceive (θεωρω). "I am beginning to perceive" from what you say, your knowledge of my private life (verse 29). See 2:23 for θεωρεω which John's Gospel has 23 times, of bodily sight (20:6,14), of mental contemplation (12:45; 14:17). See both θεωρεω and οπτομα in 1:51; 16:16.

That thou art a prophet (οτ προφητης ε συ). "That a prophet art thou" (emphasis on "thou"). She felt that this was the explanation of his knowledge of her life and she wanted to change the subject at once to the outstanding theological dispute.