At this point the prophetess is challenging Odin. She's proved her knowledge of the past, what is it that Odin really came for?
Voluspa - Norse Mythology Book - Verse 28
“Alone I sat | when the Old One sought me,
The terror of gods, | and gazed in mine eyes:
“What hast thou to ask? | why comest thou hither?
Othin, I know | where thine eye is hidden.”